I am not a tech but I love learning about many things. Having a good A/C tech is important. More importantly someone who is trustworthy. I will continue to watch his videos. Thank you for your knowledge.
I watch Brian to sharpen my understanding of refrigeration as it relates to automotive air conditioning. What a great teacher and orator. Thank you Brian for doing what you do...
I subscribed to this channel because as a restaurant owner , I’ve been taken advantage of 4-6 times over the course of 4 years between my walk in cooler and freezer , ice maker and main ac unit. I now carry my own gauges and temp probes to sadly check their work. I video and picture log all my equipment to make sure they don’t “ break “ something they should be doing . I constantly ask the tech questions and their approach and results they are aiming for to verify. I collect their answers and back research info from your channel . Thanks for these videos. They are less inclined to pull a scam on me now .
If you're going to act that fucking stupid, you might as well just do your own refrigeration since you wanna be tech anyways, don't bother company and then harass their guys. You have to be one of the worst customers to work for I do commercial supermarket refrigeration if I had a customer being like this, I would tell him to fuck off and do his own shit.
My teacher of the day! I have unlearned and re-learned a few things from your video. Thank you for the wonderful session. You added a fourth angle to my triangle.
Thanks- lots of insights that are new to me. The review of the complete diagnosing procedure was also helpful. One service manager told that first thing he would do was to put his amp probe on outdoors to get an idea about how much refrigerant charge is in the system and to see if the compressor was running. I used that idea to check a new refrigerator at my apartment which was icing up constantly. The store technicians came and told me that it was improperly sloped and not draining & that’s why it was freezing. How ever it continued to freeze up. It was only drawing about 2 amps instead of the rated 6 amps under full load. They eventually replaced that new unit with another new refrigerator. I don’t understand why it makes a loud clicking noise every time the compressor starts up that is coming from inside the cabinet and not down at the compressor.
My friend is taking night classes in south Florida. The instructors first language isn’t English. Poor kid can understand half of what the teacher says. I wish he had you. You are an excellent instructor.
23:00 I FEEL VINDICATED. I should save this video for every customer who “just wanted” their 20 year-old, never maintained attic AC in their 120 year old house “fixed” instead of replaced.
I’ve changed power heads before only to find that the valve was restricted at the body, I’d rather just change the whole thing if time and conditions permit. Good class!
I just replaced a txv yesterday. It had low suction pressure about 50 psig ( R22) SH was about 45 deg. high head pressure at 400 this was after the day shift added 22. SC way high. Took some out until suction pressure started going down. then pumped unit down, couldn't get low side below 40 psig before the compressors internal bypass opened. The head pressure got all the way down to almost 0 psig. the coil was freezing up. Put the new one in and was getting the perfect cycle. Good feeling!
We have a Lennox unit that takes 29lbs of refrigerant and it worked perfectly fine in second stage but we were getting the typical readings of a txv valve failure, low suction. I traced the line to the condenser and saw a hell of a mess of a braising job. Traced the TXV and saw that someone had melted the copper with the torch and the pipe was pinched to the point of no airflow when tested with nitrogen. Pointed it out to the Linux tech who recommended we change the solenoid first. We changed the TXV and braised everything. Pressure tested it over the weekend checked for leaks and recharged it. Works like a charm
Awesome video. From my experience with txv is I always see the outlet of the valve with frost build up and my subcool doesn’t make since or is way to high. I know so many installers who braze with out nitrogen and years down the road this is then end result. Honestly on all my service calls are maintenance I always check for dirty indoor coils , filters, ductwork and blower wheels that will cause low air flow. God bless
I purged with nitrogen on all of the systems I’ve installed in the last 20 years. I still have lots of TXV failures. They are junk, engineering in the USA and poorly made in China. Greedy corporations don’t have any problem paying their suits millions.
Really good lesson or over view. I’m recommending this lesson to the green hvac bros coming into our co. This will make a good tech out of the average tech filter changers and part changers
A note on your statement at the end about what happens if a valve core is left in the port the equalizer line connect so. On many valves, there is not a perfect seal around the rods the diaphragm pushes on to drive the valve open, so refrigerant inside the valve can leak through and push the valve closed. It will be higher pressure than the refrigerant in the evaporator coil, and has no place to go, so will force the valve too far closed. I ran into it a few times back when AS/Trane switched to providing aluminum replacement coils for their air handlers with copper coils. The coils come with no TXV, so you have to field install it, and people were not pulling the valve core out of the port. After starting the system up, the valve would start off forced wide open, flooding the coil, then slowly close down until the superheat was way too high.
I am currently pretty hungover and I can’t sleep. But I just watched your video and I understood all of the information. Wow. Such a great video, I had to subscribe. I will watch again when not hungover to make sure I retain everything. Thanks so much. Great job.
Constant super heat valve is accurate. Easiest way to check valve is measure superheat and subcool when close to or at temp. Always measure suction temp closest to TXV sensor bulb to calculate superheat. TXV, EXV, DTC valves are fun!
Pure gold Bryan, So technical you really drive home the facts, I love the videos and podcasts great reminders to strive for greatness and never assume without having all the facts Thanks again.
I guess this should go without saying but I would make sure all of the filters are clean, no slipping belt if there is one, make sure the coils are clean, in this case especially the evaporator coil, CHECK to make sure ALL dampers, diffusers, registers are open and confirm airflow. You would be surprised how many people close registers in a room not used or simply because they don't like to feel a cold draft. You can usually tell when there is a restriction or a bad txv because most times your superheat will be high. And contrary to what some people believe...if you have clean filters, coils, good airflow, then I would absolutely try warming up the txv bulb to see if there is any change in pressure at all...it's a lot easier to do than recovering the charge and changing the txv. Usually before you even get to that point you can usually find the problem. Check for a rubbed through txv capillary, look for any significant temperature differences across filter driers and watch for freezing at the txv. Finally, check to make sure the thermostat is not set too low (people have a tendency to bury it down low) and test it to make sure it stops and starts the system with reasonable accuracy. A system that runs too cold can log up oil in the evaporator coil and reduce heat transfer. Try shutting the system off for a half hour to let it stabilize and startup with a good heat load. I hope this helps.
sorry to hear that man you must of worked with some bad guys, i feel the opposite iv learned way more in the field to the point where i dont get much from alot of his videos, not bragging but alot of his material is introduction to stuff and very basic
trebrehenuf .......you’ll learn even more and much faster when you put hands-on. And more still when you’re on your own, with nobody watching you. Also, this is a trade that is very cerebral and you’ll constantly learn. Like the instructor said, even a seasoned tech can misdiagnose.
REALLY appreciate your explanation about how a restriction can actually show lower high side pressure-- as a refrigeration guy I see that all the time on LG fridges with partial cap tube restrictions.
Wasn't sure where to ask this question, but I am looking for an electronic expansion valve with a controller that will allow me to run suction pressure below zero PSI. I can't find a controller that won't fault out when trying to run Ultra load temperatures like -80F. I have to put the controller in manual mode then I can dial the electronic expansion valve to exactly what is needed whereas a TXV loses a lot of its ability to meter at these ultra-low temperatures. BTW your channel is in first place tie with the engineering mindset Channel. That's a pretty big compliment
Quick question and apologies for lack of understanding, my HVAC unit is ~10 years old, last year around winter time, we lost charge, and compressor was not working etc. Our tech after hours of testing decided it is this valve. Hence replaced it. Since then, we hear a squeaky/ chirping mechanical sound at diffrent times, and can never pinpoint the location.. the system works fine, the noise is horrible? They came to check it twice, and found no issue. Slightly low refrigerant, filled it, and the noise was not different! Any idea is appreciated
I live in SE Texas and I have been having problems with my central ac.I have a friend that is an ac guy and he put gauges on it and said it is alittle low on refrigerant but not enough to make it quit cooling all together. I think the condensor is the one that came with the house back in 1977 but in the attic, its not quite as old. The compressor runs and I have airflow. Might it be the txv? I've heard that I can cover the condenser to stop the airflow and I should not see the gauges move when the air heats up. If the txv is had, the gauges will not move. Does this sound right?
Thanks Bryan great video technician going possible back into field after 14 years in house maintenance. Probably watch again.Beer can cold days are long over. Thanks got your app on my phone!
Same. Some guys check pressures, SH, SC. Then, put txv bulb in hot water, and recheck those pressures,(suction should go up, feeding more refrigerant) you could also do ice water and txv should feed less and have lower suction. But others check pressures, SH,SC, but they even add refrigerant and see that suction deadends, again to Bryan's point, neither of these are practical. More so checking more things like discharge gas superheat off compressor. I've learned about having bad txv when changing a rusted drier, then added refrigerant charge to unit charging chart then the suction hit a deadend and wouldn't rise anymore upon adding refrigerant, the headpressure would also stack if much more refrigerant is added after that deadend. Not the best way to know, why I've been trying to find better approach.
Maximus Decimus Meridius lies, kink liquid line or clogged filter drier will increase head pressure along with liquid saturation temp which will show a subcool within range, or dirty condenser coil will raise liquid pressure and show subcool within range. Don’t feed false information to newbie techs bud.
Brian, thank you for your time and effort in making great content for us all to learn from. I work on commuter trains . We have 2 , 8 ton package units. In each unit There are 4 TXV's feeding 2 evaporator coils. There is liquid line valve and a branch circuit off the liquid line that incorporates a modulation valve, that when energized provides "Full cooling" capacity through feeding all 4 TXV's. Partial cooling capacity is accomplished by de-energizing the modulation valve and feeding only 2 TXV's . Question, Would I have to operate these units in full cooling to properly calculate SH? I've never seen a system with multiple TXV's like this before. There are no manifold gauge connections, only transducers and NTC thermistors mounted on the liquid and suction lines. We use R-407C refrigerant.
Just came across your video . Maybe you can answer this . 410A Ac system it 4 ton . My low side 156 at the gauge and 14 deg SH The high side is 287 with 1.4 deg SC Suction line temp 68 degrees. I’m thinking it’s the txv . I shut down the high side and the compressor pumped down .I’m at a loss
What if you have M low sh and the line set/evap coils are freezing..? I ran across this recently and the sh would just drop out like 5, 4, 3, 2, 1 and then .....nothing...the sc was at 5-6° head press was a little low suc press was 117-120psig and temp was 40°-43° and line set would freeze as well as the evap coils...bad TXV..? I'm fixing to chang it out and see I guess...air restrictions there are none the filter is new...should I replace the dryer first or what's the next move..?
I would clean the evaporator coil and blower fan. Plus check to make sure the TXV bulb is tight on the suction line and not on top or at the very bottom of the line. Low Superheat is the TXV over feeding refrigerant.
If everything is clean and tight look to see what type of TXV you are working with if it is a Sporlan and is adjustable I would turn the adjustment screw in one flat then check your superheat. It should rise 2 to 3 degrees.
Thank you...I was stuck..i did check and then clean all the coils inside and out as well as the fan...my readings did chang but still freeze when trying to run through a full cycle and just before pump down it starts to freeze up...so I checked and changed the TXV...it didn't have an adjustment on it and the bulb was in what I've seen as a good location I put the new one with the new TXV in the same place...as soon as I turned the refrigerant loose it even sounded different and immediately it came up to temp on the sh and all the temps and pressures came back so live and learn I guess...thanks again.
Thank you I’m working on a unit now that I have to check all this because when I got there it was frozen so I told him I would be back the next day to hook up everything again and run it properly and see what’s going on before I condemn anything
It's always taping on the txv the diaphragm with a pen. Then have a new power head and listen to the sound. Push on the diaphragm. You will see the difference. Some alco or sporlan valves willo have a kit at RSD and you don't have to replace valve body. Just make sure it's the right power head. You can use a pressure limiting power head to shut down the system in case of refrigerant lost. Pumping down and pulling a vacuum will allow you to do this.
Bryan great video as always, but ive always wondered and asked what refrigerant is used inside of a sensing bulb. It would make sense to me that the bulb would have a small amount of liquid refrigerant of whatever the system uses that its rated for but i have never been able to find documentation or get a definitive answer. Just a question ive had for 10 plus years.
Great Video but i do have some questions. So my question is 21:35. right there you have a high superheat of 27 degrees. From there you say "then you can condemn the txv". how at that moment did you figure low charge still may not still be a factor ?
Woke up this morning and AC not cooling very well. HVAC company says TXV suspected to not be good. R410a levels off on low side - to specs on high side. Advise new TXV? This company replaced our entire cooper piping a few weeks ago. Someone please help me understand what could be going on. Thank you
I always questioned the reasoning behind "clocking the bulb" so it doesn't sense the liquid. Umm, it's at the outlet of the evaporator on a copper tube. Right?
Feel like I missed something.without gauge pressure , how can you measure a suction line temp outside at 50 and say saturation temp is 40, when checking suction line temp inside it’s 47 and say it’s 7 degrees superheat? Why couldn’t it be 37?
does running your unit at a higher house temp ( thermostate set point at 81 rather that 78 degrees) help the longevity of the life of the unit? It cycles more but not as long.
but can you check a txv when a unit is off ?? like this unit is cutting on and off. cycling on and off. can you still use the super heat and sub cool method to find out if the txv is an issue ?
some aircons have check (one way) valves that will give some of the same symptoms as a bad txv. if you are thourough in the diagnosis it will become obvious but always use both hi and lo gauges and check system temps in lots of places. its been rare to have a check valve fail but they can give you a real hard time if your not aware of them.
Brian so instead of running up and down from attic to condenser unit every time you warm or cool the TXV valve bulb what about taking advantage of the Fieldpiece or Testo probes along with the Measure Quick app and watch what you pressure's and temperatures are doing. Saves alot of running around for those that have them or frees up a second person. Also can probably use an infrared terminal immature on the TXV. Just a thought 🤔
HOW can you tell if the TXV equalizer tube is connected properly to a suction line? Is there a way to test it without 10 pounds of coolant? Seriously, the suction line connection has a schraeder valve and the tube has a male piece to push it open, but how do you know that it IS opening the schraeder valve?
one time I suspected a kink and the line temp difference between ID and OD was like 15-20 degrees. I searched and sure enough the lineset was bent where it exited the wall cavity.
Thank you for this wonderful video.... I understand everything you explain in this video minus one factor. When you have a moment can you kindly explain why your DeltaT will go up when you have a bad TXV. Many thanks
If the TXV is underfeeding, there will be a noticable drop in pressure in the indoor coil. This will cause the coil to significantly drop in temperature. The air being pulled across will lose a lot more heat because of the colder than normal coil. This is what gives you a higher delta T.
Thank you Louis I've been in tons of classes and watched online videos ect... most show these numbers and temp ect... but they never show you exactly where and how there placing there test instruments which is very key...he does touch on it but showing is much better. Showing is best along with the explanation but this man seems very knowledgable so I commend him. Please do videos showing this testing and explaining it.
Can somebody please explain to me at 18:20 when he said that he goes inside to re measure hes supeheat. How do you do that? Arent you suppose to measure superheat outside on an outdoor unit? and how did it change from 14 to 10? Im having trouble understanding that scenario.
our teacher who had at the time little over 35 years in the trade told us that 3 degrees in HVAC is close enough and dont sweat it too too much ,,,,just cool that house LOL ,,,,specially in miami /ftlaud / etc southern fl,,,nice show
Would be going thru this video again but my general conclusion is if the evaporator superheat and system superheat does not have a significant difference in temperature it would most probably be another problem.pls correct me if wrong.
22 year old Trane R22 system. XE1200 with a TXV on coil. (13 Seer) Condenser coil very clean. Evap coil can't be observed, without cutting case. (Probably dirty, after 22 years.) Outdoor temp 90 degrees. Super Heat is 49. Sub Cooling is 17. (Coil paperwork calls for 16 nominal sub cooling.) Liquid line / head is 210 psi and suction line is 49 psi. Obviously freezes up and looses ability to cool below 74'. Trane factory dryer / filter on condenser does not reflect difference in temps across. Liquid pressure line temp outdoor is 85' indoor is 82'. 25' delta T. Sounds like TXV to me. I will test the TXV bulb by dipping in cooll to hot water and watch the low pressure this week. Feedback welcome!
Your head pressure is not gonna go sky high if you’re pumping down the system because you have the valve clothes so your head pressure is not gonna read anything ? Am I missing something did he say the head pressure is not gonna go up when you have a valve closed .how’s it going to test the pressure if the valves close ?
I've been watching videos of you classes you're very informative I really appreciate the information you guys are awesome
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BILLY ORR! You're the fucking man, bro!!!! You explain in my language. Keep it simple, realistic terms and terminology. Good looking homie
How to know is good fully refrigerant charged walking box freezer and cooler
Very good instructor. I have 45 years experience and 20 of that with Carrier and York. I’m still learning.
I am not a tech but I love learning about many things. Having a good A/C tech is important. More importantly someone who is trustworthy. I will continue to watch his videos. Thank you for your knowledge.
This guy is a great instructor. I don't really have that gift. So i appreciate anyone who can instruct/teach/facilitate
I watch Brian to sharpen my understanding of refrigeration as it relates to automotive air conditioning.
What a great teacher and orator. Thank you Brian for doing what you do...
You getting too long-winded with your explanation’s
I subscribed to this channel because as a restaurant owner , I’ve been taken advantage of 4-6 times over the course of 4 years between my walk in cooler and freezer , ice maker and main ac unit. I now carry my own gauges and temp probes to sadly check their work. I video and picture log all my equipment to make sure they don’t “ break “ something they should be doing . I constantly ask the tech questions and their approach and results they are aiming for to verify. I collect their answers and back research info from your channel . Thanks for these videos. They are less inclined to pull a scam on me now .
If you're going to act that fucking stupid, you might as well just do your own refrigeration since you wanna be tech anyways, don't bother company and then harass their guys. You have to be one of the worst customers to work for I do commercial supermarket refrigeration if I had a customer being like this, I would tell him to fuck off and do his own shit.
Probably one of the best HVAC channels TH-cam
THis is by far the best explained txv operation and fail operation ive seen yet... THank you for the very good lesson
Completely agree!!! 💯
This has been a great Lesson and reminder about how to do the job better on properly diagnosing the TXV.
We often use your videos for our weekly training with our techs. This one was great! Thank you again for what you do for the industry.
My teacher of the day! I have unlearned and re-learned a few things from your video.
Thank you for the wonderful session. You added a fourth angle to my triangle.
hello harvinder sir
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Excellent Brian ! You can explain the workings of refrigeration parts in an easy to understand way .
Thanks- lots of insights that are new to me. The review of the complete diagnosing procedure was also helpful. One service manager told that first thing he would do was to put his amp probe on outdoors to get an idea about how much refrigerant charge is in the system and to see if the compressor was running. I used that idea to check a new refrigerator at my apartment which was icing up constantly. The store technicians came and told me that it was improperly sloped and not draining & that’s why it was freezing. How ever it continued to freeze up. It was only drawing about 2 amps instead of the rated 6 amps under full load. They eventually replaced that new unit with another new refrigerator.
I don’t understand why it makes a loud clicking noise every time the compressor starts up that is coming from inside the cabinet and not down at the compressor.
Great video! Spot on!! The TXV has got to be the most misunderstood component of the trade.
Add air into the mix and you got yourself a long day
Watch this video a couple of times and makes me feel good to get this knowledge about txv
My friend is taking night classes in south Florida. The instructors first language isn’t English. Poor kid can understand half of what the teacher says. I wish he had you. You are an excellent instructor.
If only they taught me this well ... Fantastic class , sir , I wish I'd had my training with you guys 👍
Been doing service since 87....Love the vids....It is making me a better tech and helps me hone my skills....Thanks.
23:00
I FEEL VINDICATED.
I should save this video for every customer who “just wanted” their 20 year-old, never maintained attic AC in their 120 year old house “fixed” instead of replaced.
or a crawlspace....
Great, great class this instructor is an asset to the hvac trade. Good job.
I like the explanation of the bulb being the opening force.👍
I’ve changed power heads before only to find that the valve was restricted at the body, I’d rather just change the whole thing if time and conditions permit. Good class!
I just replaced a txv yesterday. It had low suction pressure about 50 psig ( R22) SH was about 45 deg. high head pressure at 400 this was after the day shift added 22. SC way high. Took some out until suction pressure started going down. then pumped unit down, couldn't get low side below 40 psig before the compressors internal bypass opened. The head pressure got all the way down to almost 0 psig. the coil was freezing up. Put the new one in and was getting the perfect cycle. Good feeling!
Exactly. Tech knowledge good. Experience is key
Head pressure 0psig?
Billy Monis your over charged! That’s why it won’t pump down. Txv is not your problem
@@ryanjordan6144 if the TXV has been starving the compressor long enough it will go out on high heat when pumping it down. Doesn’t mean overcharged!
We have a Lennox unit that takes 29lbs of refrigerant and it worked perfectly fine in second stage but we were getting the typical readings of a txv valve failure, low suction. I traced the line to the condenser and saw a hell of a mess of a braising job. Traced the TXV and saw that someone had melted the copper with the torch and the pipe was pinched to the point of no airflow when tested with nitrogen. Pointed it out to the Linux tech who recommended we change the solenoid first. We changed the TXV and braised everything. Pressure tested it over the weekend checked for leaks and recharged it. Works like a charm
Good video I'll be watching this one a few more times.
he is a very fast talker LOL
Great information. I'm new to this stuff, so it was lots of food for my brain. You explained it in a way I could easily understand. Thank you
Mr. Orr here is what one would call an Hvac God. Love this dude and he has helped me through many a quandary.
Awesome video. From my experience with txv is I always see the outlet of the valve with frost build up and my subcool doesn’t make since or is way to high. I know so many installers who braze with out nitrogen and years down the road this is then end result. Honestly on all my service calls are maintenance I always check for dirty indoor coils , filters, ductwork and blower wheels that will cause low air flow. God bless
great comment, thank you
I purged with nitrogen on all of the systems I’ve installed in the last 20 years. I still have lots of TXV failures. They are junk, engineering in the USA and poorly made in China. Greedy corporations don’t have any problem paying their suits millions.
I learned a lot from this video that I can use everyday. You are a HVAC wizard.
I really miss this instrumental intro to your videos. Please consider using this tune in future videos.
Great instructions on diagnosing a failed TXV
calling the TXV a constant superheat valve is a good trick for remembering what it does
on a traulsen two door commercial refrigerator can the body of the txv sit externally? outside the evaporator housing? as long and the bulb is inside?
Really good lesson or over view. I’m recommending this lesson to the green hvac bros coming into our co. This will make a good tech out of the average tech filter changers and part changers
Very informative, I've also been a last resort to change a txv,but over the years have had a few that were the TXV valve was bad..
A note on your statement at the end about what happens if a valve core is left in the port the equalizer line connect so.
On many valves, there is not a perfect seal around the rods the diaphragm pushes on to drive the valve open, so refrigerant inside the valve can leak through and push the valve closed.
It will be higher pressure than the refrigerant in the evaporator coil, and has no place to go, so will force the valve too far closed.
I ran into it a few times back when AS/Trane switched to providing aluminum replacement coils for their air handlers with copper coils.
The coils come with no TXV, so you have to field install it, and people were not pulling the valve core out of the port.
After starting the system up, the valve would start off forced wide open, flooding the coil, then slowly close down until the superheat was way too high.
I am currently pretty hungover and I can’t sleep. But I just watched your video and I understood all of the information. Wow. Such a great video, I had to subscribe. I will watch again when not hungover to make sure I retain everything. Thanks so much. Great job.
Most excellent and informative video with an excellent instructor.....Thank you Testo.
This is solid information. Presented and spoken well. Awesome.
As a tech, I love these videos.
Constant super heat valve is accurate. Easiest way to check valve is measure superheat and subcool when close to or at temp. Always measure suction temp closest to TXV sensor bulb to calculate superheat. TXV, EXV, DTC valves are fun!
Thanks!
What are signs that tell whether the screen just infront of the txv is plugged? Is their enough space to measure or even see temp differences?
Pure gold Bryan, So technical you really drive home the facts, I love the videos and podcasts great reminders to strive for greatness and never assume without having all the facts Thanks again.
Nice videos...
Can understand how txv works and fails
Please like to my channel also
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you are the best master in my country. Republic of Kosova. Thanks for all.😇
I guess this should go without saying but I would make sure all of the filters are clean, no slipping belt if there is one, make sure the coils are clean, in this case especially the evaporator coil, CHECK to make sure ALL dampers, diffusers, registers are open and confirm airflow. You would be surprised how many people close registers in a room not used or simply because they don't like to feel a cold draft. You can usually tell when there is a restriction or a bad txv because most times your superheat will be high. And contrary to what some people believe...if you have clean filters, coils, good airflow, then I would absolutely try warming up the txv bulb to see if there is any change in pressure at all...it's a lot easier to do than recovering the charge and changing the txv. Usually before you even get to that point you can usually find the problem. Check for a rubbed through txv capillary, look for any significant temperature differences across filter driers and watch for freezing at the txv. Finally, check to make sure the thermostat is not set too low (people have a tendency to bury it down low) and test it to make sure it stops and starts the system with reasonable accuracy. A system that runs too cold can log up oil in the evaporator coil and reduce heat transfer. Try shutting the system off for a half hour to let it stabilize and startup with a good heat load. I hope this helps.
Learned more in 30 minutes watching than 2 years working with journeyman.
sorry to hear that man you must of worked with some bad guys, i feel the opposite iv learned way more in the field to the point where i dont get much from alot of his videos, not bragging but alot of his material is introduction to stuff and very basic
trebrehenuf .......you’ll learn even more and much faster when you put hands-on. And more still when you’re on your own, with nobody watching you. Also, this is a trade that is very cerebral and you’ll constantly learn. Like the instructor said, even a seasoned tech can misdiagnose.
The best techs have made the most mistakes.. they learned from them and made themselves better.
Exactly...
REALLY appreciate your explanation about how a restriction can actually show lower high side pressure-- as a refrigeration guy I see that all the time on LG fridges with partial cap tube restrictions.
I found a jumped O-ring keep the needle closed on a 30 ton once, unfortunately tried ordering and changing the power head first.
flawless articulation of details
I got a tricky one. How do you troubleshoot/ adjust a circuit with multiple txv’s ?
Wasn't sure where to ask this question, but I am looking for an electronic expansion valve with a controller that will allow me to run suction pressure below zero PSI. I can't find a controller that won't fault out when trying to run Ultra load temperatures like -80F. I have to put the controller in manual mode then I can dial the electronic expansion valve to exactly what is needed whereas a TXV loses a lot of its ability to meter at these ultra-low temperatures. BTW your channel is in first place tie with the engineering mindset Channel. That's a pretty big compliment
Quick question and apologies for lack of understanding, my HVAC unit is ~10 years old, last year around winter time, we lost charge, and compressor was not working etc. Our tech after hours of testing decided it is this valve. Hence replaced it. Since then, we hear a squeaky/ chirping mechanical sound at diffrent times, and can never pinpoint the location.. the system works fine, the noise is horrible? They came to check it twice, and found no issue. Slightly low refrigerant, filled it, and the noise was not different! Any idea is appreciated
where do you place the temp sencors to measure superheat and subcooling inside
I live in SE Texas and I have been having problems with my central ac.I have a friend that is an ac guy and he put gauges on it and said it is alittle low on refrigerant but not enough to make it quit cooling all together. I think the condensor is the one that came with the house back in 1977 but in the attic, its not quite as old. The compressor runs and I have airflow. Might it be the txv? I've heard that I can cover the condenser to stop the airflow and I should not see the gauges move when the air heats up. If the txv is had, the gauges will not move. Does this sound right?
How to know is good fully refrigerant charged for walking box freezer and cooler
What if the txv is clogged and you can hear gurgling? That would be causing low pressure lock out right. Change the txv at that point?
You changed the superheat tp 27 degrees @ 20:20 in the video. Why didn`t your subcooling due to stacking liquid from a faulty TXV valve?
Thanks Bryan great video technician going possible back into field after 14 years in house maintenance. Probably watch again.Beer can cold days are long over. Thanks got your app on my phone!
I am never 100% sure when I condemn a Txv. It still feels like I'm guessing. One of my least favorite diagnoses.
Same. Some guys check pressures, SH, SC. Then, put txv bulb in hot water, and recheck those pressures,(suction should go up, feeding more refrigerant) you could also do ice water and txv should feed less and have lower suction. But others check pressures, SH,SC, but they even add refrigerant and see that suction deadends, again to Bryan's point, neither of these are practical. More so checking more things like discharge gas superheat off compressor. I've learned about having bad txv when changing a rusted drier, then added refrigerant charge to unit charging chart then the suction hit a deadend and wouldn't rise anymore upon adding refrigerant, the headpressure would also stack if much more refrigerant is added after that deadend. Not the best way to know, why I've been trying to find better approach.
Maximus Decimus Meridius lies, kink liquid line or clogged filter drier will increase head pressure along with liquid saturation temp which will show a subcool within range, or dirty condenser coil will raise liquid pressure and show subcool within range. Don’t feed false information to newbie techs bud.
Brian, thank you for your time and effort in making great content for us all to learn from. I work on commuter trains . We have 2 , 8 ton package units. In each unit There are 4 TXV's feeding 2 evaporator coils. There is liquid line valve and a branch circuit off the liquid line that incorporates a modulation valve, that when energized provides "Full cooling" capacity through feeding all 4 TXV's. Partial cooling capacity is accomplished by de-energizing the modulation valve and feeding only 2 TXV's . Question, Would I have to operate these units in full cooling to properly calculate SH? I've never seen a system with multiple TXV's like this before. There are no manifold gauge connections, only transducers and NTC thermistors mounted on the liquid and suction lines. We use R-407C refrigerant.
marty maness replace the txv and ll drier and you can’t go wrong.
i have a piston on my system, what's better Txv or piston. Should i be worried because i have a piston?
Great lecture for TXV
Just came across your video .
Maybe you can answer this .
410A Ac system it 4 ton .
My low side 156 at the gauge and 14 deg SH
The high side is 287 with 1.4 deg SC
Suction line temp 68 degrees. I’m thinking it’s the txv . I shut down the high side and the compressor pumped down .I’m at a loss
How would you measure the superheat inside I’m confuse
Txv is pure gut feeling. I change out 9 every summer
What if you have M low sh and the line set/evap coils are freezing..? I ran across this recently and the sh would just drop out like 5, 4, 3, 2, 1 and then .....nothing...the sc was at 5-6° head press was a little low suc press was 117-120psig and temp was 40°-43° and line set would freeze as well as the evap coils...bad TXV..? I'm fixing to chang it out and see I guess...air restrictions there are none the filter is new...should I replace the dryer first or what's the next move..?
I would clean the evaporator coil and blower fan. Plus check to make sure the TXV bulb is tight on the suction line and not on top or at the very bottom of the line. Low Superheat is the TXV over feeding refrigerant.
If everything is clean and tight look to see what type of TXV you are working with if it is a Sporlan and is adjustable I would turn the adjustment screw in one flat then check your superheat. It should rise 2 to 3 degrees.
Thank you...I was stuck..i did check and then clean all the coils inside and out as well as the fan...my readings did chang but still freeze when trying to run through a full cycle and just before pump down it starts to freeze up...so I checked and changed the TXV...it didn't have an adjustment on it and the bulb was in what I've seen as a good location I put the new one with the new TXV in the same place...as soon as I turned the refrigerant loose it even sounded different and immediately it came up to temp on the sh and all the temps and pressures came back so live and learn I guess...thanks again.
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Thank you I’m working on a unit now that I have to check all this because when I got there it was frozen so I told him I would be back the next day to hook up everything again and run it properly and see what’s going on before I condemn anything
It's always taping on the txv the diaphragm with a pen. Then have a new power head and listen to the sound. Push on the diaphragm. You will see the difference. Some alco or sporlan valves willo have a kit at RSD and you don't have to replace valve body. Just make sure it's the right power head. You can use a pressure limiting power head to shut down the system in case of refrigerant lost. Pumping down and pulling a vacuum will allow you to do this.
Bryan great video as always, but ive always wondered and asked what refrigerant is used inside of a sensing bulb. It would make sense to me that the bulb would have a small amount of liquid refrigerant of whatever the system uses that its rated for but i have never been able to find documentation or get a definitive answer. Just a question ive had for 10 plus years.
Thank you very much for the wonderful explanation. Rony - from Israel
Great Video but i do have some questions. So my question is 21:35. right there you have a high superheat of 27 degrees. From there you say "then you can condemn the txv". how at that moment did you figure low charge still may not still be a factor ?
Woke up this morning and AC not cooling very well. HVAC company says TXV suspected to not be good. R410a levels off on low side - to specs on high side. Advise new TXV? This company replaced our entire cooper piping a few weeks ago. Someone please help me understand what could be going on. Thank you
I always questioned the reasoning behind "clocking the bulb" so it doesn't sense the liquid. Umm, it's at the outlet of the evaporator on a copper tube. Right?
When you have a restriction will it pull vaccuum?
Feel like I missed something.without gauge pressure , how can you measure a suction line temp outside at 50 and say saturation temp is 40, when checking suction line temp inside it’s 47 and say it’s 7 degrees superheat? Why couldn’t it be 37?
does running your unit at a higher house temp ( thermostate set point at 81 rather that 78 degrees) help the longevity of the life of the unit? It cycles more but not as long.
How do you check superheat and subcool inside?
but can you check a txv when a unit is off ?? like this unit is cutting on and off. cycling on and off. can you still use the super heat and sub cool method to find out if the txv is an issue ?
some aircons have check (one way) valves that will give some of the same symptoms as a bad txv. if you are thourough in the diagnosis it will become obvious but always use both hi and lo gauges and check system temps in lots of places. its been rare to have a check valve fail but they can give you a real hard time if your not aware of them.
Very interesting class it really helped me a lot on my Jobs thank you God bless you brother
Awesome video 👍. Such a valuable information.
Brian so instead of running up and down from attic to condenser unit every time you warm or cool the TXV valve bulb what about taking advantage of the Fieldpiece or Testo probes along with the Measure Quick app and watch what you pressure's and temperatures are doing. Saves alot of running around for those that have them or frees up a second person. Also can probably use an infrared terminal immature on the TXV. Just a thought 🤔
Is there a video on the 5 pillars?
Is it true when ever TXV be replaced , the filter dryer should be replaced as well ? Plz reply
Yes
Pete Singh yes
Pete Singh - most manufacturers recommend the filter dryer replaced when a system is opened.
Great information.. well explained thank you👍👍👍👍👍👍
Does txv leak Freon ? Where r they located ? One outdoors one at furnace
HOW can you tell if the TXV equalizer tube is connected properly to a suction line? Is there a way to test it without 10 pounds of coolant? Seriously, the suction line connection has a schraeder valve and the tube has a male piece to push it open, but how do you know that it IS opening the schraeder valve?
one time I suspected a kink and the line temp difference between ID and OD was like 15-20 degrees. I searched and sure enough the lineset was bent where it exited the wall cavity.
So was the indoor temperature of the suction line more normal and the temperature of the outdoor line really low?
Thank you for this wonderful video.... I understand everything you explain in this video minus one factor. When you have a moment can you kindly explain why your DeltaT will go up when you have a bad TXV. Many thanks
If the TXV is underfeeding, there will be a noticable drop in pressure in the indoor coil. This will cause the coil to significantly drop in temperature. The air being pulled across will lose a lot more heat because of the colder than normal coil. This is what gives you a higher delta T.
Please tell me where on the inside do I take my superheat and subcooling thanks.
Thank you Louis I've been in tons of classes and watched online videos ect... most show these numbers and temp ect... but they never show you exactly where and how there placing there test instruments which is very key...he does touch on it but showing is much better. Showing is best along with the explanation but this man seems very knowledgable so I commend him. Please do videos showing this testing and explaining it.
How do you calculate your indoor sc or sh without knowing the indoor pressure
Can somebody please explain to me at 18:20 when he said that he goes inside to re measure hes supeheat. How do you do that?
Arent you suppose to measure superheat outside on an outdoor unit? and how did it change from 14 to 10?
Im having trouble understanding that scenario.
Cause suction line pressure drop 14 to 10
As he mentioned earlier when pressure goes up temp goes up when pressure goes down temp goes down
our teacher who had at the time little over 35 years in the trade told us that 3 degrees in HVAC is close enough and dont sweat it too too much ,,,,just cool that house LOL ,,,,specially in miami /ftlaud / etc southern fl,,,nice show
Very nicely explained Bryan. Thanks
What factors are considered by the factory to determine that a txv is used for one refrigerant or another?
I will answer your question in a Q/A video
Would be going thru this video again but my general conclusion is if the evaporator superheat and system superheat does not have a significant difference in temperature it would most probably be another problem.pls correct me if wrong.
Very helpful thanks,can I have a question,it is possible to charge freon r404a while the expansion valve r22? Thats for walking freezef
Great job sir , from Trinidad and tobago.
Deon's air conditioning services here
22 year old Trane R22 system. XE1200 with a TXV on coil. (13 Seer) Condenser coil very clean. Evap coil can't be observed, without cutting case. (Probably dirty, after 22 years.) Outdoor temp 90 degrees. Super Heat is 49. Sub Cooling is 17. (Coil paperwork calls for 16 nominal sub cooling.) Liquid line / head is 210 psi and suction line is 49 psi. Obviously freezes up and looses ability to cool below 74'. Trane factory dryer / filter on condenser does not reflect difference in temps across. Liquid pressure line temp outdoor is 85' indoor is 82'. 25' delta T. Sounds like TXV to me. I will test the TXV bulb by dipping in cooll to hot water and watch the low pressure this week. Feedback welcome!
Is there any content on hooking up a ductless blower to a central air condenser?
Your head pressure is not gonna go sky high if you’re pumping down the system because you have the valve clothes so your head pressure is not gonna read anything ? Am I missing something did he say the head pressure is not gonna go up when you have a valve closed .how’s it going to test the pressure if the valves close ?