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I cannot thank you enough, our old mini-split went out this week. We were unable to get a service tech...in the end I was able to get a replacement from a supply house and install it as this brutal cold spell moved in. It took me all day to install and perform all of the tests. In the end, I completed the task just around midnight in 17 degree weather. Waking up to a nice warm house was worth it. Thanks again.
I followed this TH-cam and your other ones to the letter! I installed a two zone Mitsubishi Mini-Split. Everything worked perfectly! Thank you so much! I have probably forfeited the warranty by not using a licensed installer but have saved us north of $1K. I even bought the tools you recommended. The Yellow Jacket flaring tool was the most impressive. I did buy the two valve removal tools you also recommended however Mitsubishi use 1/4" not 5/16" for the service valve so I just used a simple gate valve for the vacuum gauge. I was able to get a sustained vacuum down to 160 microns which held for over an hour using the triple evacuation method. Thanks again😀😀😀😀
Your method makes sense for a professional who wants to save time. For a DIYer I think it makes made sense to add one hour wait after the initial 200 micron evacuation. This will allow the lines to come up to ambient temperature and avoid frozen water in the lines. Then pull down a deep vacuum again before releasing refrigerant. A pro can’t afford an extra hour but a DIYer can. And you avoid messing with nitrogen and all the extra connects and disconnects and opportunities to screw up.
Very good demonstration. One thing I will point out is you should always either fully open or fully close a high pressure tank, nitrogen, oxygen, argon. These tanks use back seating valves and if you ever saw a packing gland go with 2000 psi behind it go, its not fun
Thanks Craig, you are the best educator out there. What i believe is lacking is a cumulative video on servicing a single port mini split which has a 410A issue. I’m talking about an existing (not new installation) unit with cooling issues - we need a single video (or a 2 or 3 part video) starting at recovery thru repair, leak check (pressure test), triple vacuum & recharge. I know you have many videos but it’s confusing to try & piece them together because the systems are different & many of the units shown have more than one service port. I think there will be a tremendous demand for such a comprehensive video for a complete service on a 410A single port mini split. Thanks for the great videos, i am ordering your book today.
Yes. These are very common in other countries and typical issues are the complex inverter board (you want an "inverter checker device") Or one of the 5-6 temp sensors. Sometimes the temp sensors out by say 10-20 %, or operate in a non linear fashion, these faults may not flag an error code and take a bit of nutting out.
Craig you are doing great work with these videos. Very very clear, helpful and no bologne. Very thorough on the purging and clearing lines, every time. How many times have you done a flare with no nut. I made fun of other youtubers doing it and said, i'll end up doing it. Then no less than 2 hours later. I did it. It has to be a badge of honor. My kid was watching, they have to see you make mistakes and how you handle it. I just said, always have a little extra to do this exact thing.
Great video. I wasn’t prepared for how much force would be applied to the core removal tool after the valves were opened to release refrigerant. The pressure really pushed on the core removal tool and slammed it back like a piston! Also there was a bunch of pressure left in the removal tool after the schrader valve was screwed back in. I ended up hooking up the blue gauge on my line set to the removal tool and releasing the pressure into the gauge because I was worried I hadn’t properly reinstalled the valve. I was relieved to find I had installed the valve successfully :)
Perfect video. You touched all basses of how to evacuate the system properly and most importantly you showed us how to break the vacuum with nitrogen. Thank you Craig for the very valuable information.
I am a slow learner. I will watch this 3 times and then just before a new installation, so I don't miss any of these valuable steps! Thank you SO Much Craig! This is so informational!
I followed this set-up but I kept the 1/4" flare only loosely connected and pushed nitrogen through the line-set and the indoor unit and at just slightly above atmospheric. I torqued it last. I then pressure tested it at 300 PSI for a couple hours, released it and I used the Accutools BluVac vacuum gauge with the Bluetooth app that graphs the vacuum rise over time. I don't know how that compares to the triple vac method (my manufacture didn't require it) but worked like a charm. I used fresh high-quality Navac vacuum oil, a 2-stage pump, and the TruBlue hoses connected to the 5/16 valve core removal tool like you have. I also bought a Yellow Jacket pressure gauge that goes directly on the 1/4" valve core removal tool in place of the vacuum gauge for the pressure testing. Pulled it down to 65-micron, then with a 15-minute decay held at 90-micron. I released the refrigerant and was good to go. Thanks for your VERY informative videos.
Kevin, thanks for the info. I've been wondering about alternative methods to vacuum a multi-zone mini with long line-sets (45' & 40' of 3/8", and 20' of 5/8"). I can achieve an initial deep vacuum reading (= or > 250 microns), but the decay test always rises considerably to above 1,000 microns. And trying to purge nitrogen through all of that was an exercise in futility. For the record, I did perform a nitrogen pressure test of 500-520 psi for 48hours. The 20 psi variant is due to day and night temperature changes.
Once again I learn something. I've been using the Schrader valve core tools with the stem still in place on tool with vaccum guage. The vaccum was pulling quickly and rising fast. Thanks craig for the correction. I assume with me not removing the stem at the tool will have a similar effect as the one at the service port. I'm 18 years in the trade and try to learn something new every day. I was wondering what was going on and now I know. Thanks again 👍👍.
Same here I’ve always removed the Schrader valve core so I can vac out quicker. Trouble is I always drop the core and I can never find it again. Good job I have plenty of spare valve cores on my van😂
@@Upliftyourbrothers Good question, and what about breaking the vacuum if you don't have a bottle or nitrogen. I'm thinking CO2 could be used. I think the deal with nitrogen is that it is a gas free of any water. I've always heard the term "dry nitrogen." Anyway back to your question, I'm thinking of just running the vacuum pump for a more extended period of time.
As you stated correctly, the value of nitrogen comes from the purging action, or as we call it the “nitrogen sweep” Always nitrogen sweep your line set, before you make the final connections. And don’t place too much faith in the Apions. They will start leaking sooner rather than later.
One more comment, I purchased your book and have found it to be very comprehensive in regard to its subject. In the future, could you possibly update with information pertinent to mini-splits to cover simple one wall units to more complex systems with branch boxes, cassettes, etc... Thank you much appreciated.
AC Service Tech LLC do you have to do this? I suppose it’s faster than just letting the ice melt in the pipes but could you hypothetically leave it in vacuum overnight and then revacuum the next morning?
Thank you for the videos! As the vacuum pump doesn’t have a non return valve, doesn’t the vacuum in the hose pull vacuum oil out of the pump and into the hose? This happened to me.
Usually I very much enjoy your video's. This one is a little beyond me. I have done HVAC for about 55 yrs. and we used to pull a full vacuum one time and let it set for awhile and then charge the system. Never had an issue if the system was tight and a sporlan filter dryer was used. Way the triple vacuum is a little beyond me? Thanks for great video's.
Waterman, yeah the point of the video is that you see the standing vacuum test held below 500 microns for the single and also for the triple. The triple went and held a little deeper. You wouldn't really need to do a triple evac unless there were water in the tubing. Thanks!
Do you fit filter driers on split systems in America? In the U.K we only fit filter driers to fridge systems, but never in split systems. Is it regulation in the U.S or just personal preference?
Thank you for your videos! I’ve been learning a lot. I don’t know whether to get the Yellowjacket digital adjustable torque wrench or just the Yellowjacket torque wrench kit for mini split installations. I know both do a great job but can’t decide between the two.
I was also stuck with the same choice. But I went for the digital one because the kit had more complaints (on Amazon) regarding its accuracy and clicking, especially if not broken in correctly. The digital one had no complaints regarding its accuracy or clicking.
@AC Service Tech LLC would it be better practice to break vacuum pump hose after pulling vacuum, closing service tool check valve, and turning off the vacuum pump but before doing the standing vacuum test? This way, there would be no vacuum contribution to the measured vacuum reading in case there was a faulty core service tool check valve? Thanks for the videos!
Have you looked into the AccuTools tru blue evacuation set? I believe the triple evacuation procedure is in reference to the engineers handbook. And that was last updated in the 60's and they were probably in reference to the old single stage vacuum pumps which by now-a-days standards is the equivalent to a less than 1 CFM pump.
To do a nitrogen purge you could just crack the flare fitting on the high side port. I don't know about running the nitrogen backwards through the expansion valve at the evaporator coil inside the structure. I haven't heard of moisture freezing inside the lines as a result of evacuating a system. Allegedly ice is removed through the process of sublimation where a solid turns to vapor immediately not going through a liquid state. There should be no oil in the lines of a new installation. Having now watched to the end, I really think you should replace the Schrader core prior to the last vacuum. Your way works but it was even tricky for you, I'm not comfortable with it at all.
I also think the idea of the triple evacuation is to just speed up the process. It's probably more effective to pull a deep vacuum, "sweep" with nitrogen, and repeat the process several times rather than running a vacuum over a longer period of time.
How are you determining when the vacuum goes a few psig positive and it’s time to cut off the N2? Would you want to swap the micron for a pressure gauge? Are you just kind of guesswing it here based on experience?
First I want to thank you for all your info I am learning a ton between your videos and books. I have a few questions on procedures in this video I hope you can clarify. #1. You mention you always remove the cores out of you VCRT (valve core removal tool) and install the second VCRT to isolate the vacuum gauge. While I understand this and it makes sense from a speed and convivence POV but wouldn't it be better to leave the core in the 5/16" VCRT and not use the the 2nd 1/4" VCRT and simply detach the vacuum gauge before charging refrigerant? It would seem like there is less chance of a pocket of air getting trapped in the 2nd VCRT #2. During the triple evacuation every time you charge nitro and disconnect it you open the valve on the 1/4 VCRT before connecting the vacuum gauge, essentially opening the lineset to ambient air, wouldn't it be better to leave it closed and then reinstall the vacuum gauge then open the valve on the VCRT so you are not introducing extra air into the lineset? Or is there an issue with vacuum gauges and positive pressure even though it should be very low positive pressure if only using 5psi of nitro? #3. As far as doing a nitrogen purge on a mini spit that doesnt have a service port on the liquid line couldnt you just leave the flare nut a little loose on the liquid line while all the others are torqued and purge it that way and then torque the liquid line as last step while under very low flow? #4. Finally would it be ok or better to set it up so you wouldnt have to disconnect/reconnect anything at all? Im picturing starting with the service port. Then the 5/16 VCRT either with or without the core, and vacuum gauge either like you have it or directly to the VCRT with a core in place. then on the the back side of the 5/16" VCRT either a charging T or something like a Appion speed Y so you can have both the nitro and the vacuum hooked with ball valve hoses and then just alternate between opening and closing the ball valves on the hoses as needed to alternate between vacuum and nitro during the triple evacuation. That way you are never introducing air into the lineset. Then just pull everything after the 5/16 VCRT and then charge with refrigerant. I hope that all made sense.
We don't normally use the fancy "valve core remover" in these situation just the basic screwdriver type core remover. Then reinsert valve core at about 2-5psi. Ideal when the fancy tool is in a too bulky situation
Would it not have been possible to begin by leaving the upper flare nut loose, flowing nitrogen from the lower line to push most of the air out through the upper line before tightening the upper line? Seems like that would make for quite a bit less air/moisture in the system when you pull the first vacuum.
Can this procedure be used on a mini-split with a branch box and ceiling cassettes? If possible, can you do a video on a mini-split with a branch box and ceiling cassettes? Thanks
I have a weird situation: First, I removed the valve core and pressure tested with nitrogen to 300psi. I let it sit for 1 hour and saw no change. I use the exact setup you show (different pump) to pull vacuum and it takes about 2 mins to pull down to 300um. Then I close the valve to the vacuum pump and instantly lose all vacuum (gauge reads blank). Then I re-open the valve to the vacuum pump it drops back down to
When you release the pressure after adding Nitrogen, isn't air allowed back into the system before you hook up the micron gauge and vacuum again. I'm a bit confused.
@@acservicetechchannel Definitely. We had a perfect 24 hour pressure test, then triple evacuated. During the standing micron test, we went from 140 to 270 in fairly steady increments over 30 minutes. We called it good but I was just curious as to why that might happen.
I’m just curious about your decay test. You only recommend a 10 minute test? Whilst I’m still in school, they are teaching us to let it stand for, at the least, an hour. You teach me so much more than the school does.
By 10 minutes, it usually doesn't rise any more, maybe 10 microns for the next ten hours in most of my trials. By the end of the ten minutes if should have leveled off. You would know if it keeps rising. On conventional systems I keep the indoor fan running anyway to provide heat at the coil so that would negate the time factor and the pressure test was already done prior to this. We need to figure out fast yet correct ways of doing things in the field so we get the job done quickly and effectively, thanks!
@@acservicetechchannel Honestly I think that's what your method is all about. The most efficient way of getting a system up and running in the shortest amount of time at the least cost while not endangering the atmosphere.
When you vent the N2 to atmosphere you've defeated the purpose of the N2 purge and reintroduced atmosphere along with all the humidity back into the system.
@@Fighter4Street He could leave the gauge attached, lever it off and use the shrader valve on the black appion valve to add nitrogen, then release the nitrogen through the shrader until there is just little left so no atmosphere gets in. Start the vacuum pump, and gently open the valve lever until it's fully open. Then open the gauge lever. I could be missing something though.
@@Fighter4Street First of all get rid of the valve core removal tool. It's completely unnecessary unless you're over 23' of lineset. My experience has been 23' took 30ish minutes to pump down whereas an 8' lineset took 5 minutes to pump down without removing the core. So the solution is to use 2 tees. That leaves 4 connection points. 1 goes to the unit to pump down the system, 1 for the vac gauge with a shut-off valve, 1 for N2 line with a shut-off valve, 1 for the vac pump with a shut-off valve. You never have to vent with that method. You never lose vacuum either as you could using a valve core removal tee. Once you pump down with this 2 tee set up you release the refrigerant to the pressurize the system including your 2 connected tees. At that point you unscrew the 2 tee assembly from the unit. Quickly. You lose a tiny bit of refrigerant equiv to what you'd losing purging the air in the tee as in this video near the end. Having written all that, i'm not clear what the sensitivity is of using N2 vs not ever using N2 and just pumping down. It could be the N2 helps remove more water when you vent with it reducing the slow boil off time of water in the sytem slowly raising the pressure.
@@flyingyakdeath I used to build custom marine systems 30 years ago before R12 was outlawed. At that time we just purged with R12 and really didn't even need a vacuum pump. Personally I think the Nitrogen deal is just a comparatively inexpensive not harmful to the atmosphere gas that can be used for pressure testing, then additionally several short pull downs with a follow up nitrogen sweep reduces the service time to get the system up and running. There is usually more than one way of accomplishing something. I also said before, and I know for an absolute fact that a small drier added to the liquid line removes moisture and acids better than vacuuming at least on a system that has been operating and maybe leaked on the low side and went into vacuum, pulling in air and moisture while operating.
I haven't finish watching, but what he could or should do is put the schrader back into the system before the final vacuum. At that point I would pull it down for the final time and then release refrigerant into the system. You don't want to do that until you are positive you don't have any leaks or accumulated moisture in the lines. I probably shouldn't comment until I see how he finishes off. I've been away from the trade a long time and a lot has changed.
The hose you use for nitrogen, is the ball valve part of the hose or is it separate? And would you recommend keeping that hose for just nitrogen or could it be used for charging also?
Some Fujitsu mini-split units have a depressed service valve setup which makes it impossible to install a valve core removal tool. What is the valve core removal tool setup for these units?
what size tank is that for nitrogen and is is supposed to be a very specific "dry" nitrogen or do I just go up to welding supply shop and as for a tank of nitrogen? also do the gauges at the welding place work or do they have to be specifically for hvac?
Great tutorial. I have a question a little off topic. Can the vapor line and refrigerant line be bound together with tape or copper wire and then insulated? Does this cause a electro-static reaction or temprature problem with a 1 ton mini-split? I've read arguments for binding together and directions not to, but no explanation why not to bind together. Thanks.
My experience with marine refrigeration systems has been that you can tape the two lines together mostly to warm the return line to avoid frost accumulation. If you use wire it would be best to be certain to use bare copper wire or an insulated wire, because steel or aluminum might cause electrolysis. On the minisplit system I purchased the lines are insulated separately . It could be that when the unit converts to heating that having the lines taped together may reduce the efficiency of the heating. Maybe others more with more experience will comment.
Yes absolutely and I had a note in the video that on larger conventional systems, you could break the first vacuum at 1,000 the second at 600 and break the final vacuum at 300 or less, thanks!
Could you solder a 'T' into the opposite end of the line set to flow nitrogen through? Put a ball valve on it and solder a cap onto it once you perform the nitrogen purge of the line set.
Craig, I need to see if this information is correct for a 30 lbs. cylinder of R22. Does the cylinder empty weight 5lbs. 6oz. and is the volume 822 cubic inches? Thanks for your excellent videos.
Thanks Craig! I`m glad that you have done this videos on ductless mini-split systems. To be fair these are very common where I live, and your videos have been very educative for me. Please can you male a video or something how to check that these systems are low/high in refrigerant while these systems have only one port to connect? Meaning that it works in the same way superheat and subcooling. How can we check? Thank`s!
Another outstanding video. Thank you! It seems that when you open the top VCRT to let the nitrogen pressure out of the lineset (and before you put the vac gauge back on), that it is allowing moist outside air into the lineset. Is this acceptable because you are going to be immediately pulling a deep vacuum, or am I missing something? Thank you.
Have you ever heard of or used refrigerant gas instead of nitrogen to break the vacuum for the triple evacuation? My boss have reprimanded me for using nitrogen. Explanation is that refrigerant gas is dryer. Feedback please? I’m begging you and I would love some science behind it if there is any.
You're a great teacher! My question is, I have a 5 ton Trane xl19i . It calls for a 60amp breaker. I started to notice that my 50 amp contactor has started pitting. Would you recommend I stick with the 50amp contactor when I replace it , or could I go with a 60amp contactor?
Are you using soap bubbles or an electronic leak tester. I don't know if the is a electronic tester for nitrogen. Somehow you have to pressurerise the system and then check it with soap bubbles anywhere there is a mechanical joint like a flare , or even the schrader itself. His video starts out after the pressure test. He originally pressurized it with nitrogen and checked to see if it leaked down. Or maybe he also ran soap bubbles over the flare joints. If you tighten a flare too much you can pull the flare off. At that point you will have to cut the flared end off and redo it getting more tubing from somewhere. Hopefully you left some slack.
Hey Craig should you keep the head units on the system if you can do a sweep and push any oil out and through the head units for these split systems? I just wonder about any old oil being caught up in the evap coils of the heads. I was told by someone from a supply house to open the flares at the head unit and blow from there.
Thank u for this video.very clear instruction on a tripple vaccum test.Craig can u do a video on how to set pressures,on different refrigetants so as to set L.P/H.P. switches.Thanks
Are the new R32 systems becoming popular in the U.S now? In the U.K these R32 units especially on mini splits are popping up everywhere. The pressures are also practically identical to R410a. Although I’m yet to see any chiller systems run on this new gas. What’s the primary vacuum reading in the U.S microns or Torr?
Would inserting the core before releasing the Freon be considered a bad practice? I guess the air inside the chamber of the removal tool would enter the system rather than the pressure of the system pushing that air out.
Yes that would be a bad practice and I have seen a lot of people doing that. You would loose the vacuum that you just spent all that time doing, thanks!
how do you purge, pressure test and vacuum a mini-split that is old and has no charge in the outdoor unit? Do I need to use magnet to fully open the EEV, Also is any other component blocking the path to do a complete purge or vacuum of the entire system? Also is it even achievable with only one service port? thanks for any advice
@@glennhendricks4111 First close off the valves to the compressor/ condensing unit and the pressurize it with some type of gas and find the leak with soap bubbles. The leak is most likely in one of the flare joints or around the service valves. The problem is an older unit that ran out of refrigerant is a lot of moisture has probably been pulled into the system and the compressor oil is contaminated. Even a deep vacuum won't get all the water out from under the oil. However if you think you got the leak stopped vacuum as best you can for a long period of time, and then add a drier and moisture indicating site glass for at least the amount of time it takes for the moisture indicating sight glass that the system is free of moisture. Then I guess at that point based on what people are saying, pump the refrigerant into the high side reservoir and remove the drier. Unless you have a lot of experience you may need to call a good repairman who knows how to deal with it. I'm a very strong believer in the effectiveness of driers at cleaning up a system.
I have to finishing watching the video, but it seems to me best practice would be to reinsert the schrader prior to the final vacuum pull down. The final pull down would not be as critical in terms of speed and even pulling as deep a vacuum. The reason for the deep vacuum is moisture removal. But that should be entirely gone before the final pull down. I can definitely see value in the so called "triple vacuum method."
Yes it vacuums both lines. The difference is that we don't have a metering device half way down the tubing loop like in a conventional system. The metering device in a minisplit is in the outdoor unit, thanks!
You are vacuuming both lines from the low side at the service port. It's somewhat of a sketchy method. In the old days, we used to pull from the high and low side simultaneously with a more complex valving system. What I see is that these newer systems have been somewhat simplified from a manufacturing point of view, but more complex from a servicing point of view.. The less valves and less mechanical joints such as flare fittings, the less chance for leaks. Smaller units such as window AC's and home refrigerators are completely sealed with no service port initially. They never leak gas. Anywhere there's a flare there can be a leak. Compression fittings are the worst. Second to that pipe thread. Flare is the best but still can have problems for a variety of reasons. I see nowadays they have outrageously expensive plastic washers that can be used to stop troublesome leaks.
how do you purge, pressure test and vacuum a mini-split that is old and has no charge in the outdoor unit? Do I need to use magnet to fully open the EEV, Also is any other component blocking the path to do a complete purge or vacuum of the entire system? Also is it even achievable with only one service port? thanks for any advice
What about if you have a multi city Mitsubishi ? Do you just vacuum with valve core tool from one circuit if the system is completely void on refrigerant since it will pull through the compressor ?
Your question is complex. I guess you are describing a situation where the refrigerant has leaked out almost entirely. In that case you would vacuum the entire system, not just the connection lines. The system is just one large loop of tubing. The compressor is a circulation pump. To that you have a condensing coil and evaporation coil in the circuit. You pull a vacuum at the service valve. In these mini spits the refrigerant can be pumped into the receiver if you understand the procedure. Contaminated systems present a more difficult situation that requires more complete servicing which may or may not be entirely successful in the long term.
This book is everything that has to do with refrigerants, preparing the system for refrigerant, checking the charge, and troubleshooting but does not go into the electrical side. I am working on a separate book for that presently. The full outline and sample pages for this book are at www.acervicetech.com/ac-book and the book is also for sale on amazon, thanks!
I can tell you that a fan relay would be activated with a temperature sensor, pressure switch, or even a door switch, unless it runs continuously. To trouble shoot it, check the fan itself first to see if it actually works and it's a control problem. After that you usually bypass the control in some way to see if you can force the fan on. If the fan works when a control mechanism is eliminated then in all likelihood the control is at fault. But again you have to first know that fan itself is not the problem. You can usually check the relays themselves with an ohm meter for continuity of the windings, and to see if the is an electrical connection when the points are closed. Electrical contacts can become dirty, disappear or weld themselves shut. You need to try to figure that out. or just replace it if the fan works when it is bypassed.
You can get a nitrogen purge once on a mini split, if you do so just before attaching & torquing your 1/4" connection at the outdoor unit. Assuming your pressure test passes, there should only be nitrogen in the lineset from that point on.
@@Bostonn617 1: Flare attach and torque indoor unit. 2: Flare attach and torque outdoor suction line. 3: Flare (but don't attach) outdoor liquid line. 4: Then attach nitrogen to the service port, do your purge. 5: Attach and torque the liquid line. This way you have mostly nitrogen in the lines, and were able to run nitrogen through the lineset, not just in and out the service port.
I can never get my core removal tool onto the bottom valve it's too long and the unit/lower valve is too close to the ground it's driving me nuts! so I can never pull the core on bottom valve on mini splits only the higher valves when doing multiple heads.
Maintaining a vacuum is extremely difficult. I think he said in another comment that he has been able to hold it for a period of 5 hours or so. A lot depends on the condition of your charging hoses. Usually if they are old, they will not hold a vacuum well.
Great video, one question regarding a Nitrogen pressure test prior to this test. If you are installing a cooling only mini-split that operates at lower pressure, do you need to perform this or is the micron test sufficient?
@@acservicetechchannel Just got my Nitrogen tank today and will install my Mitsubishi later this week following this method. I have relied heavily on your videos and appreciate your attention to detail.
In my opinion that's what you should do. I've got to watch the end of the video. I can't see doing it any other way. The only thing I can think of is that they want neutral pressure on the refrigerant valves before opening them.
Is the 3/4” metal cap with hole that you attach after reinserting the valve core an item that’s available for purchase? I searched in the parts list but only see regular caps. Does the hole have to be drilled into a regular cap? And if so, what size is the hole? The re-insertion of the valve core seems to be one of the trickiest steps. You can’t tighten the vct too tightly or the o-ring will squish and prevent the core from moving past. Too loose and the valve could potentially shoot out under pressure and leak all of the coolant. If anyone knows about the cap with hole used to test for any escaping air/coolant, please comment. Thanks!
My opinion is the you can use something else at least on new systems with fresh tubing. It's probably not ideal or preferred. You wouldn't want to do a triple evacuation breaking the vacuum with air. I say just pull a longer single vacuum if you are trying to do it with out all the preferred gasses. I did work on R-12 systems for years and never had any nitrogen. But that was before R-12 was banned and all the regulations came in. In principle you want to keep the system free of moisture in particular and any other contaminants that can result from soldering.
Is it imperative that you remove the Schrader core? I have a unit that you can't pull the cores out on since it's at an angle (fujitsu) also my vacuum decay was pretty stable over 20-30 min with minimal rise. Over 15 minutes it came up 50 microns to 100-110. I walked away and went to bed and checked unit in morning about 7 hours later and the vacuum decayed to 550 microns. Does anyone think that's ok? I figure I'm ok on this one. 500 psi pressure test for 24 hours with only a slight dip in psi and I figure it's from temperature drop.
It just picks up any moisture left in the system. He's saying ice, but I doubt that. Maybe it's true. I never heard of it before unless it's on a running system that actually froze up internally because of moisture in the lines. On a new system it seems highly doubtful. A pressure drop does cause a temperature drop so it is theoretically possible. I just have never heard of it before watching this video.
I don't understand how the nitrogen gets all the way through both sides of the line set in a longer line when there is no service valve on the small side.
You probably have a leak but it could be in the connecting hoses not the actual system or your vacuum pump is shot. Maybe the test instrument is out of calibration. Test it with just the vacuum pump by itself, not connected to a system.
You could but you may want to reapply oil or nylon to the flare face, torque to 11ft lbs and pressure test. You could do that if needed. Like I said you could also do the nitrogen blow through for the oil if you had a prob pulling a vacuum. In most cases you can just do a single evac deeper and that's fine, thanks!
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I cannot thank you enough, our old mini-split went out this week. We were unable to get a service tech...in the end I was able to get a replacement from a supply house and install it as this brutal cold spell moved in. It took me all day to install and perform all of the tests. In the end, I completed the task just around midnight in 17 degree weather. Waking up to a nice warm house was worth it. Thanks again.
Wow! Thanks for sharing your Massive undertaking in cold weather!
I followed this TH-cam and your other ones to the letter! I installed a two zone Mitsubishi Mini-Split. Everything worked perfectly! Thank you so much! I have probably forfeited the warranty by not using a licensed installer but have saved us north of $1K. I even bought the tools you recommended. The Yellow Jacket flaring tool was the most impressive. I did buy the two valve removal tools you also recommended however Mitsubishi use 1/4" not 5/16" for the service valve so I just used a simple gate valve for the vacuum gauge. I was able to get a sustained vacuum down to 160 microns which held for over an hour using the triple evacuation method.
Thanks again😀😀😀😀
Awesome! Thanks!
Your method makes sense for a professional who wants to save time. For a DIYer I think it makes made sense to add one hour wait after the initial 200 micron evacuation. This will allow the lines to come up to ambient temperature and avoid frozen water in the lines. Then pull down a deep vacuum again before releasing refrigerant. A pro can’t afford an extra hour but a DIYer can. And you avoid messing with nitrogen and all the extra connects and disconnects and opportunities to screw up.
Best HVAC teacher in the world.
Thank you for your support!
Very good demonstration. One thing I will point out is you should always either fully open or fully close a high pressure tank, nitrogen, oxygen, argon. These tanks use back seating valves and if you ever saw a packing gland go with 2000 psi behind it go, its not fun
Thanks Craig, you are the best educator out there. What i believe is lacking is a cumulative video on servicing a single port mini split which has a 410A issue. I’m talking about an existing (not new installation) unit with cooling issues - we need a single video (or a 2 or 3 part video) starting at recovery thru repair, leak check (pressure test), triple vacuum & recharge. I know you have many videos but it’s confusing to try & piece them together because the systems are different & many of the units shown have more than one service port. I think there will be a tremendous demand for such a comprehensive video for a complete service on a 410A single port mini split. Thanks for the great videos, i am ordering your book today.
Thanks a lot Charlie and thanks for letting me know what you would like to see!
Yes. These are very common in other countries and typical issues are the complex inverter board (you want an "inverter checker device") Or one of the 5-6 temp sensors. Sometimes the temp sensors out by say 10-20 %, or operate in a non linear fashion, these faults may not flag an error code and take a bit of nutting out.
@@acservicetechchannelI could really use that vid right about now as well 😂
Craig you are doing great work with these videos. Very very clear, helpful and no bologne. Very thorough on the purging and clearing lines, every time. How many times have you done a flare with no nut. I made fun of other youtubers doing it and said, i'll end up doing it. Then no less than 2 hours later. I did it. It has to be a badge of honor. My kid was watching, they have to see you make mistakes and how you handle it. I just said, always have a little extra to do this exact thing.
Thank you just took a class today on dual pump down and charge release today!!!
The best HVAC school ever! .
Thanks Graig.
Awesoem, thanks!
Great video. I wasn’t prepared for how much force would be applied to the core removal tool after the valves were opened to release refrigerant. The pressure really pushed on the core removal tool and slammed it back like a piston! Also there was a bunch of pressure left in the removal tool after the schrader valve was screwed back in. I ended up hooking up the blue gauge on my line set to the removal tool and releasing the pressure into the gauge because I was worried I hadn’t properly reinstalled the valve. I was relieved to find I had installed the valve successfully :)
Perfect video.
You touched all basses of how to evacuate the system properly and most importantly you showed us how to break the vacuum with nitrogen.
Thank you Craig for the very valuable information.
I am a slow learner. I will watch this 3 times and then just before a new installation, so I don't miss any of these valuable steps! Thank you SO Much Craig! This is so informational!
Thank You
I have been watching you for two years as I continue to learn
Awesome to hear, thanks Matthew!
I followed this set-up but I kept the 1/4" flare only loosely connected and pushed nitrogen through the line-set and the indoor unit and at just slightly above atmospheric. I torqued it last. I then pressure tested it at 300 PSI for a couple hours, released it and I used the Accutools BluVac vacuum gauge with the Bluetooth app that graphs the vacuum rise over time. I don't know how that compares to the triple vac method (my manufacture didn't require it) but worked like a charm. I used fresh high-quality Navac vacuum oil, a 2-stage pump, and the TruBlue hoses connected to the 5/16 valve core removal tool like you have. I also bought a Yellow Jacket pressure gauge that goes directly on the 1/4" valve core removal tool in place of the vacuum gauge for the pressure testing. Pulled it down to 65-micron, then with a 15-minute decay held at 90-micron. I released the refrigerant and was good to go. Thanks for your VERY informative videos.
Nobody does it better than you.
Kevin, thanks for the info. I've been wondering about alternative methods to vacuum a multi-zone mini with long line-sets (45' & 40' of 3/8", and 20' of 5/8"). I can achieve an initial deep vacuum reading (= or > 250 microns), but the decay test always rises considerably to above 1,000 microns. And trying to purge nitrogen through all of that was an exercise in futility. For the record, I did perform a nitrogen pressure test of 500-520 psi for 48hours. The 20 psi variant is due to day and night temperature changes.
Once again I learn something. I've been using the Schrader valve core tools with the stem still in place on tool with vaccum guage. The vaccum was pulling quickly and rising fast. Thanks craig for the correction. I assume with me not removing the stem at the tool will have a similar effect as the one at the service port. I'm 18 years in the trade and try to learn something new every day. I was wondering what was going on and now I know. Thanks again 👍👍.
I am really glad that this helped!
Same here I’ve always removed the Schrader valve core so I can vac out quicker. Trouble is I always drop the core and I can never find it again. Good job I have plenty of spare valve cores on my van😂
Any reason why I couldn’t use inert welding gas instead of 100% nitrogen?
@@Upliftyourbrothers Good question, and what about breaking the vacuum if you don't have a bottle or nitrogen. I'm thinking CO2 could be used. I think the deal with nitrogen is that it is a gas free of any water. I've always heard the term "dry nitrogen." Anyway back to your question, I'm thinking of just running the vacuum pump for a more extended period of time.
New to the channel, I appreciate your natural ability to teach 👍🏻🇺🇸
I appreciate that!
As you stated correctly, the value of nitrogen comes from the purging action, or as we call it the “nitrogen sweep” Always nitrogen sweep your line set, before you make the final connections. And don’t place too much faith in the Apions. They will start leaking sooner rather than later.
Great step by step Triple Vaccume. Thanks for a really good explanation.
Well done! A true professional! 👏
One more comment, I purchased your book and have found it to be very comprehensive in regard to its subject. In the future, could you possibly update with information pertinent to mini-splits to cover simple one wall units to more complex systems with branch boxes, cassettes, etc... Thank you much appreciated.
Great info! This was a necessary video. Don't think most people are doing this.
Glad to help, thanks!
AC Service Tech LLC do you have to do this? I suppose it’s faster than just letting the ice melt in the pipes but could you hypothetically leave it in vacuum overnight and then revacuum the next morning?
Hi on ur vac pump, and hose….is it 3/8” sae to 1/4” flare? Or
Is is 1/2” sae to 1/4” flare?
And where to get that hose?
Thank you for the videos! As the vacuum pump doesn’t have a non return valve, doesn’t the vacuum in the hose pull vacuum oil out of the pump and into the hose? This happened to me.
Usually I very much enjoy your video's. This one is a little beyond me. I have done HVAC for about 55 yrs. and we used to pull a full vacuum one time and let it set for awhile and then charge the system. Never had an issue if the system was tight and a sporlan filter dryer was used. Way the triple vacuum is a little beyond me? Thanks for great video's.
I think with mini splits driers are not recommended
Waterman, yeah the point of the video is that you see the standing vacuum test held below 500 microns for the single and also for the triple. The triple went and held a little deeper. You wouldn't really need to do a triple evac unless there were water in the tubing. Thanks!
Yes you do not add a filter drier in the field installed line set on a mini split, thanks!
@@acservicetechchannel Thanks for the reply. Why not add a drier? Thanks
Do you fit filter driers on split systems in America? In the U.K we only fit filter driers to fridge systems, but never in split systems. Is it regulation in the U.S or just personal preference?
Thank you for your videos! I’ve been learning a lot. I don’t know whether to get the Yellowjacket digital adjustable torque wrench or just the Yellowjacket torque wrench kit for mini split installations. I know both do a great job but can’t decide between the two.
I was also stuck with the same choice. But I went for the digital one because the kit had more complaints (on Amazon) regarding its accuracy and clicking, especially if not broken in correctly. The digital one had no complaints regarding its accuracy or clicking.
@AC Service Tech LLC would it be better practice to break vacuum pump hose after pulling vacuum, closing service tool check valve, and turning off the vacuum pump but before doing the standing vacuum test? This way, there would be no vacuum contribution to the measured vacuum reading in case there was a faulty core service tool check valve? Thanks for the videos!
Have you looked into the AccuTools tru blue evacuation set?
I believe the triple evacuation procedure is in reference to the engineers handbook. And that was last updated in the 60's and they were probably in reference to the old single stage vacuum pumps which by now-a-days standards is the equivalent to a less than 1 CFM pump.
To do a nitrogen purge you could just crack the flare fitting on the high side port. I don't know about running the nitrogen backwards through the expansion valve at the evaporator coil inside the structure. I haven't heard of moisture freezing inside the lines as a result of evacuating a system. Allegedly ice is removed through the process of sublimation where a solid turns to vapor immediately not going through a liquid state. There should be no oil in the lines of a new installation. Having now watched to the end, I really think you should replace the Schrader core prior to the last vacuum. Your way works but it was even tricky for you, I'm not comfortable with it at all.
I also think the idea of the triple evacuation is to just speed up the process. It's probably more effective to pull a deep vacuum, "sweep" with nitrogen, and repeat the process several times rather than running a vacuum over a longer period of time.
How are you determining when the vacuum goes a few psig positive and it’s time to cut off the N2? Would you want to swap the micron for a pressure gauge? Are you just kind of guesswing it here based on experience?
First I want to thank you for all your info I am learning a ton between your videos and books. I have a few questions on procedures in this video I hope you can clarify. #1. You mention you always remove the cores out of you VCRT (valve core removal tool) and install the second VCRT to isolate the vacuum gauge. While I understand this and it makes sense from a speed and convivence POV but wouldn't it be better to leave the core in the 5/16" VCRT and not use the the 2nd 1/4" VCRT and simply detach the vacuum gauge before charging refrigerant? It would seem like there is less chance of a pocket of air getting trapped in the 2nd VCRT #2. During the triple evacuation every time you charge nitro and disconnect it you open the valve on the 1/4 VCRT before connecting the vacuum gauge, essentially opening the lineset to ambient air, wouldn't it be better to leave it closed and then reinstall the vacuum gauge then open the valve on the VCRT so you are not introducing extra air into the lineset? Or is there an issue with vacuum gauges and positive pressure even though it should be very low positive pressure if only using 5psi of nitro? #3. As far as doing a nitrogen purge on a mini spit that doesnt have a service port on the liquid line couldnt you just leave the flare nut a little loose on the liquid line while all the others are torqued and purge it that way and then torque the liquid line as last step while under very low flow? #4. Finally would it be ok or better to set it up so you wouldnt have to disconnect/reconnect anything at all? Im picturing starting with the service port. Then the 5/16 VCRT either with or without the core, and vacuum gauge either like you have it or directly to the VCRT with a core in place. then on the the back side of the 5/16" VCRT either a charging T or something like a Appion speed Y so you can have both the nitro and the vacuum hooked with ball valve hoses and then just alternate between opening and closing the ball valves on the hoses as needed to alternate between vacuum and nitro during the triple evacuation. That way you are never introducing air into the lineset. Then just pull everything after the 5/16 VCRT and then charge with refrigerant. I hope that all made sense.
We don't normally use the fancy "valve core remover" in these situation just the basic screwdriver type core remover. Then reinsert valve core at about 2-5psi. Ideal when the fancy tool is in a too bulky situation
Great customer information !
Thanks a lot Jack!
How would this change if you had two service ports on the high and low?
Do they make a cap with hole, or is this something u made?
Thk u.
You make.
I don't know if I can get nitrogen, will propane work? I have plenty of that.
I vaccumed it an everything was fine i didnt use nitrogen will that cause a problem
Very well explained. Enough so that I may actually attempt this.
Thanks.
You can do it!
Would it not have been possible to begin by leaving the upper flare nut loose, flowing nitrogen from the lower line to push most of the air out through the upper line before tightening the upper line? Seems like that would make for quite a bit less air/moisture in the system when you pull the first vacuum.
I’m new to this but won’t the vacuum pull the nitrogen out?
Can this procedure be used on a mini-split with a branch box and ceiling cassettes? If possible, can you do a video on a mini-split with a branch box and ceiling cassettes? Thanks
I have a weird situation: First, I removed the valve core and pressure tested with nitrogen to 300psi. I let it sit for 1 hour and saw no change. I use the exact setup you show (different pump) to pull vacuum and it takes about 2 mins to pull down to 300um. Then I close the valve to the vacuum pump and instantly lose all vacuum (gauge reads blank). Then I re-open the valve to the vacuum pump it drops back down to
Is that ok to have nitrogen tank laying down?
Hi happy new year.
must be screwed tightly or loosely when the vacuum pump is running;
When you release the pressure after adding Nitrogen, isn't air allowed back into the system before you hook up the micron gauge and vacuum again. I'm a bit confused.
Really outstanding video. Thanks for sharing your experience. Going to be following your procedure this weekend!
Glad it was helpful!
@@acservicetechchannel Definitely. We had a perfect 24 hour pressure test, then triple evacuated. During the standing micron test, we went from 140 to 270 in fairly steady increments over 30 minutes. We called it good but I was just curious as to why that might happen.
I’m just curious about your decay test. You only recommend a 10 minute test? Whilst I’m still in school, they are teaching us to let it stand for, at the least, an hour. You teach me so much more than the school does.
By 10 minutes, it usually doesn't rise any more, maybe 10 microns for the next ten hours in most of my trials. By the end of the ten minutes if should have leveled off. You would know if it keeps rising. On conventional systems I keep the indoor fan running anyway to provide heat at the coil so that would negate the time factor and the pressure test was already done prior to this. We need to figure out fast yet correct ways of doing things in the field so we get the job done quickly and effectively, thanks!
@@acservicetechchannel Honestly I think that's what your method is all about. The most efficient way of getting a system up and running in the shortest amount of time at the least cost while not endangering the atmosphere.
do you still need a VCRT when using a digital gauge?
When you vent the N2 to atmosphere you've defeated the purpose of the N2 purge and reintroduced atmosphere along with all the humidity back into the system.
What should he have done differently then? How can you avoid venting the N2 into the atmosphere?
@@Fighter4Street He could leave the gauge attached, lever it off and use the shrader valve on the black appion valve to add nitrogen, then release the nitrogen through the shrader until there is just little left so no atmosphere gets in. Start the vacuum pump, and gently open the valve lever until it's fully open. Then open the gauge lever. I could be missing something though.
@@Fighter4Street First of all get rid of the valve core removal tool. It's completely unnecessary unless you're over 23' of lineset. My experience has been 23' took 30ish minutes to pump down whereas an 8' lineset took 5 minutes to pump down without removing the core. So the solution is to use 2 tees. That leaves 4 connection points. 1 goes to the unit to pump down the system, 1 for the vac gauge with a shut-off valve, 1 for N2 line with a shut-off valve, 1 for the vac pump with a shut-off valve. You never have to vent with that method. You never lose vacuum either as you could using a valve core removal tee. Once you pump down with this 2 tee set up you release the refrigerant to the pressurize the system including your 2 connected tees. At that point you unscrew the 2 tee assembly from the unit. Quickly. You lose a tiny bit of refrigerant equiv to what you'd losing purging the air in the tee as in this video near the end. Having written all that, i'm not clear what the sensitivity is of using N2 vs not ever using N2 and just pumping down. It could be the N2 helps remove more water when you vent with it reducing the slow boil off time of water in the sytem slowly raising the pressure.
@@flyingyakdeath I used to build custom marine systems 30 years ago before R12 was outlawed. At that time we just purged with R12 and really didn't even need a vacuum pump. Personally I think the Nitrogen deal is just a comparatively inexpensive not harmful to the atmosphere gas that can be used for pressure testing, then additionally several short pull downs with a follow up nitrogen sweep reduces the service time to get the system up and running. There is usually more than one way of accomplishing something. I also said before, and I know for an absolute fact that a small drier added to the liquid line removes moisture and acids better than vacuuming at least on a system that has been operating and maybe leaked on the low side and went into vacuum, pulling in air and moisture while operating.
Ty for the video. I would like to ask every time you release the nitrogen don’t you introduce air back in the system?
I haven't finish watching, but what he could or should do is put the schrader back into the system before the final vacuum. At that point I would pull it down for the final time and then release refrigerant into the system. You don't want to do that until you are positive you don't have any leaks or accumulated moisture in the lines. I probably shouldn't comment until I see how he finishes off. I've been away from the trade a long time and a lot has changed.
@@JoeLinux2000 thank you for taking the time
Very informative,
A question why do you need to slightly loosen off the core remover from the service port to insert the schrader ?
8:38 - I understand laying the N₂ bottle down to get it in the video shot; but, don't you have a risk of liquid N₂ coming out of the tank here?
The hose you use for nitrogen, is the ball valve part of the hose or is it separate? And would you recommend keeping that hose for just nitrogen or could it be used for charging also?
Some Fujitsu mini-split units have a depressed service valve setup which makes it impossible to install a valve core removal tool. What is the valve core removal tool setup for these units?
what size tank is that for nitrogen and is is supposed to be a very specific "dry" nitrogen or do I just go up to welding supply shop and as for a tank of nitrogen? also do the gauges at the welding place work or do they have to be specifically for hvac?
I've been wondering the same. What did you figure out?
60lbs
Well presented and thoroughly explained. Great job! Thank you!
Glad it was helpful!
Are you vacuuming the system with nitrogen in it?
Do you guys have material for automotive AC with R134a?
Great tutorial. I have a question a little off topic. Can the vapor line and refrigerant line be bound together with tape or copper wire and then insulated? Does this cause a electro-static reaction or temprature problem with a 1 ton mini-split? I've read arguments for binding together and directions not to, but no explanation why not to bind together. Thanks.
My experience with marine refrigeration systems has been that you can tape the two lines together mostly to warm the return line to avoid frost accumulation. If you use wire it would be best to be certain to use bare copper wire or an insulated wire, because steel or aluminum might cause electrolysis. On the minisplit system I purchased the lines are insulated separately . It could be that when the unit converts to heating that having the lines taped together may reduce the efficiency of the heating. Maybe others more with more experience will comment.
It is a special size for that core valve also?
Could we do that on a regular conventional system. Not a mini split unit ..??
Yes absolutely and I had a note in the video that on larger conventional systems, you could break the first vacuum at 1,000 the second at 600 and break the final vacuum at 300 or less, thanks!
AC Service Tech LLC Great ..!! Thanks for the answer.
Could you solder a 'T' into the opposite end of the line set to flow nitrogen through? Put a ball valve on it and solder a cap onto it once you perform the nitrogen purge of the line set.
I was thinking something along this line too
Craig, I need to see if this information is correct for a 30 lbs. cylinder of R22. Does the cylinder empty weight 5lbs. 6oz. and is the volume 822 cubic inches? Thanks for your excellent videos.
Thanks Craig! I`m glad that you have done this videos on ductless mini-split systems. To be fair these are very common where I live, and your videos have been very educative for me.
Please can you male a video or something how to check that these systems are low/high in refrigerant while these systems have only one port to connect? Meaning that it works in the same way superheat and subcooling. How can we check? Thank`s!
Another outstanding video. Thank you! It seems that when you open the top VCRT to let the nitrogen pressure out of the lineset (and before you put the vac gauge back on), that it is allowing moist outside air into the lineset. Is this acceptable because you are going to be immediately pulling a deep vacuum, or am I missing something? Thank you.
Hardly any moist air gets in, everything is at atmospheric pressure at that point and the tubes are skinny.
Have you ever heard of or used refrigerant gas instead of nitrogen to break the vacuum for the triple evacuation? My boss have reprimanded me for using nitrogen. Explanation is that refrigerant gas is dryer. Feedback please? I’m begging you and I would love some science behind it if there is any.
You're a great teacher! My question is, I have a 5 ton Trane xl19i . It calls for a 60amp breaker. I started to notice that my 50 amp contactor has started pitting. Would you recommend I stick with the 50amp contactor when I replace it , or could I go with a 60amp contactor?
Great video for vacuum test, would like to know detailed step by step pressure test on new install mini split, cannot find leak.
Are you using soap bubbles or an electronic leak tester. I don't know if the is a electronic tester for nitrogen. Somehow you have to pressurerise the system and then check it with soap bubbles anywhere there is a mechanical joint like a flare , or even the schrader itself. His video starts out after the pressure test. He originally pressurized it with nitrogen and checked to see if it leaked down. Or maybe he also ran soap bubbles over the flare joints. If you tighten a flare too much you can pull the flare off. At that point you will have to cut the flared end off and redo it getting more tubing from somewhere. Hopefully you left some slack.
Hey Craig should you keep the head units on the system if you can do a sweep and push any oil out and through the head units for these split systems? I just wonder about any old oil being caught up in the evap coils of the heads. I was told by someone from a supply house to open the flares at the head unit and blow from there.
Thank u for this video.very clear instruction on a tripple vaccum test.Craig can u do a video on how to set pressures,on different refrigetants so as to set L.P/H.P. switches.Thanks
Kenneth, thanks for letting me know what you would like to see!
Yes, that would be important. You may be able to find the info on line or from the installation manual.
Are the new R32 systems becoming popular in the U.S now? In the U.K these R32 units especially on mini splits are popping up everywhere. The pressures are also practically identical to R410a. Although I’m yet to see any chiller systems run on this new gas. What’s the primary vacuum reading in the U.S microns or Torr?
What is the name of the Schrader core removal tool you use?
Appion
Good video as always 👍🏾
Thanks Dee Pope!
Would inserting the core before releasing the Freon be considered a bad practice? I guess the air inside the chamber of the removal tool would enter the system rather than the pressure of the system pushing that air out.
Yes that would be a bad practice and I have seen a lot of people doing that. You would loose the vacuum that you just spent all that time doing, thanks!
how do you purge, pressure test and vacuum a mini-split that is old and has no charge in the outdoor unit? Do I need to use magnet to fully open the EEV, Also is any other component blocking the path to do a complete purge or vacuum of the entire system? Also is it even achievable with only one service port? thanks for any advice
@@glennhendricks4111 First close off the valves to the compressor/ condensing unit and the pressurize it with some type of gas and find the leak with soap bubbles. The leak is most likely in one of the flare joints or around the service valves. The problem is an older unit that ran out of refrigerant is a lot of moisture has probably been pulled into the system and the compressor oil is contaminated. Even a deep vacuum won't get all the water out from under the oil. However if you think you got the leak stopped vacuum as best you can for a long period of time, and then add a drier and moisture indicating site glass for at least the amount of time it takes for the moisture indicating sight glass that the system is free of moisture. Then I guess at that point based on what people are saying, pump the refrigerant into the high side reservoir and remove the drier. Unless you have a lot of experience you may need to call a good repairman who knows how to deal with it. I'm a very strong believer in the effectiveness of driers at cleaning up a system.
I have to finishing watching the video, but it seems to me best practice would be to reinsert the schrader prior to the final vacuum pull down. The final pull down would not be as critical in terms of speed and even pulling as deep a vacuum. The reason for the deep vacuum is moisture removal. But that should be entirely gone before the final pull down. I can definitely see value in the so called "triple vacuum method."
Great Video. So for mini-split system, Do we still do vacuum for both liquid line and suction line ? Thank you.
Yes it vacuums both lines. The difference is that we don't have a metering device half way down the tubing loop like in a conventional system. The metering device in a minisplit is in the outdoor unit, thanks!
You are vacuuming both lines from the low side at the service port. It's somewhat of a sketchy method. In the old days, we used to pull from the high and low side simultaneously with a more complex valving system. What I see is that these newer systems have been somewhat simplified from a manufacturing point of view, but more complex from a servicing point of view.. The less valves and less mechanical joints such as flare fittings, the less chance for leaks. Smaller units such as window AC's and home refrigerators are completely sealed with no service port initially. They never leak gas. Anywhere there's a flare there can be a leak. Compression fittings are the worst. Second to that pipe thread. Flare is the best but still can have problems for a variety of reasons. I see nowadays they have outrageously expensive plastic washers that can be used to stop troublesome leaks.
how do you purge, pressure test and vacuum a mini-split that is old and has no charge in the outdoor unit? Do I need to use magnet to fully open the EEV, Also is any other component blocking the path to do a complete purge or vacuum of the entire system? Also is it even achievable with only one service port? thanks for any advice
I think you asked this previously
Great video
Glad you enjoyed it
What about if you have a multi city Mitsubishi ? Do you just vacuum with valve core tool from one circuit if the system is completely void on refrigerant since it will pull through the compressor ?
Your question is complex. I guess you are describing a situation where the refrigerant has leaked out almost entirely. In that case you would vacuum the entire system, not just the connection lines. The system is just one large loop of tubing. The compressor is a circulation pump. To that you have a condensing coil and evaporation coil in the circuit. You pull a vacuum at the service valve. In these mini spits the refrigerant can be pumped into the receiver if you understand the procedure. Contaminated systems present a more difficult situation that requires more complete servicing which may or may not be entirely successful in the long term.
great video. does your ac book explain how fan relays work and how heat sequencers work. and the electrical theory . on them.
This book is everything that has to do with refrigerants, preparing the system for refrigerant, checking the charge, and troubleshooting but does not go into the electrical side. I am working on a separate book for that presently. The full outline and sample pages for this book are at www.acervicetech.com/ac-book and the book is also for sale on amazon, thanks!
I can tell you that a fan relay would be activated with a temperature sensor, pressure switch, or even a door switch, unless it runs continuously. To trouble shoot it, check the fan itself first to see if it actually works and it's a control problem. After that you usually bypass the control in some way to see if you can force the fan on. If the fan works when a control mechanism is eliminated then in all likelihood the control is at fault. But again you have to first know that fan itself is not the problem. You can usually check the relays themselves with an ohm meter for continuity of the windings, and to see if the is an electrical connection when the points are closed. Electrical contacts can become dirty, disappear or weld themselves shut. You need to try to figure that out. or just replace it if the fan works when it is bypassed.
Can you do a video on troubleshooting mini-split units?
You can get a nitrogen purge once on a mini split, if you do so just before attaching & torquing your 1/4" connection at the outdoor unit. Assuming your pressure test passes, there should only be nitrogen in the lineset from that point on.
What do you mean?
@@Bostonn617 1: Flare attach and torque indoor unit. 2: Flare attach and torque outdoor suction line. 3: Flare (but don't attach) outdoor liquid line.
4: Then attach nitrogen to the service port, do your purge. 5: Attach and torque the liquid line.
This way you have mostly nitrogen in the lines, and were able to run nitrogen through the lineset, not just in and out the service port.
Great video my friend 👏🏻👏🏻👏🏻
Very nice video I am An Ac technician
Thanks and glad to help GK Tech!
I like the tools you use. big thumbs up and sub.
I can never get my core removal tool onto the bottom valve it's too long and the unit/lower valve is too close to the ground it's driving me nuts! so I can never pull the core on bottom valve on mini splits only the higher valves when doing multiple heads.
Should you get absolutely no rise in microns during the decay test after it settles out?
Maintaining a vacuum is extremely difficult. I think he said in another comment that he has been able to hold it for a period of 5 hours or so. A lot depends on the condition of your charging hoses. Usually if they are old, they will not hold a vacuum well.
So when vacuuming, we are looking that the microns do not rise above 500? any movement under that is ok?
Les than 500 microns insures a dry system.
Great video, one question regarding a Nitrogen pressure test prior to this test. If you are installing a cooling only mini-split that operates at lower pressure, do you need to perform this or is the micron test sufficient?
We still do a nitrogen pressure test so if there is a leak, the vacuum wont pull humid air into the tube through the leak spot, thanks!
@@acservicetechchannel Just got my Nitrogen tank today and will install my Mitsubishi later this week following this method. I have relied heavily on your videos and appreciate your attention to detail.
Have you had problems with the appion valve core remover. I've heard (I havent experience it yet) that they been leaking from the lever.
I haven't had any problems with them during filming, use in the field or my students at school. I have had others leak though but not these.
Sir,how do I test split air conditioner swing motor ok in circuit and out from circuit
Why not put the valve core in before releasing the refrigerant into the pipes?
In my opinion that's what you should do. I've got to watch the end of the video. I can't see doing it any other way. The only thing I can think of is that they want neutral pressure on the refrigerant valves before opening them.
You will introduce air to the system, as the pin doesn’t stay in the tool while vaccuming.
Thanks for the videos
Glad to help Justin!
Is the 3/4” metal cap with hole that you attach after reinserting the valve core an item that’s available for purchase? I searched in the parts list but only see regular caps. Does the hole have to be drilled into a regular cap? And if so, what size is the hole?
The re-insertion of the valve core seems to be one of the trickiest steps. You can’t tighten the vct too tightly or the o-ring will squish and prevent the core from moving past. Too loose and the valve could potentially shoot out under pressure and leak all of the coolant.
If anyone knows about the cap with hole used to test for any escaping air/coolant, please comment. Thanks!
Is air that has the moisture removed suitable as a replacement for Nitrogen for leak testing of residential 5ton or less units?
We just use dry inert gasses, thanks!
My opinion is the you can use something else at least on new systems with fresh tubing. It's probably not ideal or preferred. You wouldn't want to do a triple evacuation breaking the vacuum with air. I say just pull a longer single vacuum if you are trying to do it with out all the preferred gasses. I did work on R-12 systems for years and never had any nitrogen. But that was before R-12 was banned and all the regulations came in. In principle you want to keep the system free of moisture in particular and any other contaminants that can result from soldering.
@@JoeLinux2000 Thank you for your reply
So what cools the compressor?
The refrigerant itself cools the hermetic compressor, thanks!
I’ve been having a hard time pulling vacuum on mini splits i seem to be staying at 600 microns
Is it imperative that you remove the Schrader core? I have a unit that you can't pull the cores out on since it's at an angle (fujitsu) also my vacuum decay was pretty stable over 20-30 min with minimal rise. Over 15 minutes it came up 50 microns to 100-110. I walked away and went to bed and checked unit in morning about 7 hours later and the vacuum decayed to 550 microns. Does anyone think that's ok? I figure I'm ok on this one. 500 psi pressure test for 24 hours with only a slight dip in psi and I figure it's from temperature drop.
You posted a long time ago, so I'm sure it has been resolved, but I would say you are good to go as 500 microns is considered good.
What is the purpose of triple nitrogen? Thanks
It just picks up any moisture left in the system. He's saying ice, but I doubt that. Maybe it's true. I never heard of it before unless it's on a running system that actually froze up internally because of moisture in the lines. On a new system it seems highly doubtful. A pressure drop does cause a temperature drop so it is theoretically possible. I just have never heard of it before watching this video.
I don't understand how the nitrogen gets all the way through both sides of the line set in a longer line when there is no service valve on the small side.
Hey Craig, what if you do the triple and still don't get it down well below 500?
You probably have a leak but it could be in the connecting hoses not the actual system or your vacuum pump is shot. Maybe the test instrument is out of calibration. Test it with just the vacuum pump by itself, not connected to a system.
Why wouldn't you crack the high side flare and do a nitrogen purge for a few minutes?
You could but you may want to reapply oil or nylon to the flare face, torque to 11ft lbs and pressure test. You could do that if needed. Like I said you could also do the nitrogen blow through for the oil if you had a prob pulling a vacuum. In most cases you can just do a single evac deeper and that's fine, thanks!
I do that myself however you have to be careful not to split the flair when tightening back up. I’ve done that a few times😬
@@acservicetechchannel Good to know.
@@matty6848 The less you mess with a flare the better off you'll be.