As an electronics tech, something that caught my eye was that line of dirt on the bottom of the main board. Dirt can become conductive, especially when the humidity rises and then you'll get all kinds of weird problems. Just part of how I roll when it comes to big picture, inspecting, and doing it right. I use an acid brush that I've cut the bristles to half length to stiffen them. That and a vacuum cleaner.
I know absolutely nothing about HVAC. I have no idea why TH-cam recommended this channel but I'm glad they did. I have no idea why this is so entertaining. I think it's the way you explain things so well. I'm subbing.
Super videos, 50 years in our trade but still learning. I will never forget my instructor so many years ago saying for the first five years you know nothing. Keep safe.
i have seen one guy got his hat caught in it n set off sprinker ROFL easy way get away with it put big cup with duck tape on it that way doesnt get caught on something when ya coming up there
Haha, yes, love it! lol each time I saw it in the video just thinking of it and it being caught on video too. I'm glad I didn't choose your trade when I left school but I love watching you doing such an important job in often horrible conditions. Respect to you.
Almost certainly mandated by code - would be here in Aus. So in reality the failure is on the part of the architect providing insufficient space for access (fairly normal from experience) or failing to provide other suitable access -,eg external. That of course brings in a much bigger picture and that has always been the issue with facilities design for engineering services. In the end, it’s the service tech. wearing the problem. I think a cage over the outside of the head would avoid triggering the head but might reduce available space too much. Another two inches on the access and much better!
God bless you for working at so many restaurants, I imagine it’s like pulling teeth at times convincing people they actually need things repaired/replaced
It's the worst thing to come into a fault half way through the fix, stuff's been removed and the bolts have wandered off ..... great to see just that little bit of detail. Makes life so much easier, especially when you've bolts of different lengths.... that's always fun. I've the same issues at work, you can't fix everything first time. Sometimes you get lucky, most times you open up a whole can of worms....... it's why I like my job. It's boring for the most part but there are moments of happiness when I'm sorting problems out.
Hey Chris. Great job and video again. The haters sometimes criticize you for using tech support. But we mechanics don’t know each and every machine. The folks with tech support many times make us look like heroes. When I was in the field; I loved Lennox units. At Emcor when I was there, we took care of a lot of National accounts. Many times it was a hassle to deal with them but bottom line; they put food on my table. Most of the Target stores that I serviced in San Diego county had those Lennox boxcars. I hope that your business is doing excellent. Stay safe and careful out there. Have a great Thursday evening with your family. God bless.
With a proving circuit, you now have 3 possible states: - Open: wire is broken - Shorted: Wire melted or detector tripped. - Supervisory state: All is fine. How it often work is with a simple resistor. Basically the resistor 'soft short' the wiring at the end of it. If the panel see the resistor, then the wiring is intact. Open then something is broken, and sorted it mean it tripped or the wire shorted/melted. Some system will use two resitors, one end of line (the first one) plus another series one with the detector. Now you can have 4 states: open, close, EOL resistor or the tripped resistor. Those can therefore detect between the shorted or tripped condition. Those can help to avoid some nuisance alarm due to a nail in the wiring.
I've been watching your Videos for the past two weeks now, even though I'm not even remotely connected to HVACR I'm an electrical engineer, but I picked up a fair bit and after reading up on some terms that meant nothing to me like superheat etc. I even start to understand how and why you do things. So you do a pretty good job on explaining and methods. Probably will never put that knowledge to any greater use since the HVACR guy at our company didn't even take me serious as I told him that it sounds like a bearing in the compressor is about to die (compressor died 2 Weeks later, took them 3 months to get a new unit installed, industrial carrier cold water circuit, those roof direct air units are very uncommon in europe) but it never hurts to know things outside of your job, so thanks for providing :)
Don’t worry about the sprinkler. I’m a truck driver and had a load to an enclosed strip mall that had a height hog 13’6.5”. My truck is 13’6”. The day before they had lowered the sprinklers 2”. I took off 4 sprinkler heads; it looked like a Roman fountain goin off on the top of my trailer. It was quite scenic. Not!
Looked up Spec on that VFD (FR-D720-100-NA). It looks border line in it's sizing. It's rated at 10 A up to 122°F. It should have over temp protection. But from all that dirt I see from the cooling fan means the heat sink is most likely dirty. Thus reducing it's cooling capacity. If this is an common issue look at replacing them with the FR-D720-165-NA model. It's rated for 16.5 A.
It's also probably running closer to 150 F ambient mounted in that unit on the top of a roof in So Cal. You can see two of the main filter caps have died, and this was quite likely from the prolonged high temperature soaking. I strongly suspect those caps failing was the root cause of the VFD failure, not a (stupidly) borderline current rating.
@@lwilton Not to mention dirty supply from all the contractors and motors etc in the various AC's etc/ But you are right the caps are not going to like sitting out there in the hot sun all day at 150f/65.55556c. That's going to be a bit hot even for the micro controller inside of the VFD too. I'd go as far as 50% de-rate them, go find one that will supply the required amps after 50% de-rating it.
Nice job: You can't beat the older style units that have only relays that operate the stages and systems. Sometimes the new tech stuff cost more that it saves. Thanks for the video.
@@gordonrichardson2972 thank our "environmentalist" buddies. Don't get me wrong - I'm all for conservation. But how about conservation with some common sense that's not completely divorced from reality?
Yeah. I'm not in the industry, but I have to wonder if that VFD and all the circuitry that controls it is really more economical than a two speed motor controlled by relays and contactors.
@Sean That is throwing the baby out with the bathwater. Nothing wrong with using chips and such where it makes sense. It just doesn't make sense to use them for ~5% energy savings while sacrificing ~25% in the reliability.
Thank you, for this video. I have not seen these here in Michigan, yet, but given the energy regulations and the closing of coal fired plants, it's only a matter of time before I have to deal with these VFDs. Thanks to you, and your experience, I will have a leg up. Thank You.
Real electrical engineers know how to do multi-speed motors with no electronics. This gratuitous electronic is being put in there simply to generate service calls. True variable speed units like the mini-splits I installed in my retirement cabin are a different matter. Even then the chicoms are running the power transistors at absolute max rating which is why one driver board has already failed.
suggestion: When filming the prodigy boards - try using a slightly longer shutter time (in most phone models if you use a phone to film - have a "advanced" or "pro" mode to set shutter). You might need to reduce apeture tough. If your phone or camera allows saving profile, try getting a good profile for just prodigy boards, and then save it as 2 profiles, one for "normal" filmning and one for "prodigy". Play around with the camera settings - should be pretty easy if you have a prodigy board at home, until you get a nice view.
Usually wouldn't work as the outdoor sun is too bright for a slower shutter speed. We use ND filters for that, but finding one for phone cameras might be difficult. An easier way might be to just put sunglasses / welding goggles in front of the camera and let the auto exposure adjust.
That opening clip... I cringed so hard. Brought back memories of working in a certain home improvement chain's local distribution center. A sprinkler head was RIGHT next to the warehouse racks, and there were many than occasions where we had to shut down and evacuate because someone on powered equipment had taken off the head and triggered the fire alarm. I kept suggesting to anyone that would listen that we should install a small cage of rebar around it to protect it from impact, but nobody cares what the fireman's son has to say about the fire alarm system. OOOF, those exploded capacitors on the VFD are definitely the cause of the tripped breaker! I wonder if they failed due to high temperatures on the roof? High temps cause the dielectric to breakdown and the caps then basically become shorts. Mitsubishi also had an issue with bad capacitors in some of their cars' ECMs in the '90s because they used a cheaper brand instead of their own parts - they dried out under the harsh temperatures inside a car and failed. As you said, putting the VFDs in a cooler environment will extend their lifespan. Judging by the incredible scorch marks inside the dead VFD, I guarantee some HV arced over to the LV sections, if I had to offer a theory (much simpler, but similar to I wilton's theory) the faulty caps became dead short, high voltage arced to low voltage sections, and from there basically grenaded the daughter board and probably parts of the main board.
Pretty fair guess about what happened to that unit: Looking at the VFD innards, it is immediately obvious that two of the main filter caps have failed. Others may have also failed, but those two probably were enough. They were probably bad enough that they were supplying AC to the VFD logic when it should have been DC. This probably wouldn't have damaged the chips, but it trashed their operation, and they got completely confused. Somewhere in their confusion, they turned on two or maybe all three phases at once, shorting the line across the power MOSFETs in the driver part of the board. The result was a lot of black greasy smoke and shrapnel all over the inside of the VFD. A lot of nice greasy conductive smoke, probably along with a nice hot arc for a very short time. Probably the arc migrated from the power MOSFETs into the logic chips. From there it fed back along the control lines and momentarily put 208 onto the logic of the main control board. The VFD control may be partially isolated, but not enough so. The short pulse of HV didn't completely smoke the control, but it was enough to confuse the heck out of it, and possibly fry some logic as well as wiping out the flash/EEPROM memory in the unit. You are probably right that having that VFD in a more climate controlled room would have preserved it. I suspect if you put a recording thermometer in the VFD case you would find that it is way over the max continuous operating temperature for a good part of the day in summer. I'm not an air conditioning guy, so I might seriously consider going to Lowes and getting a 5000 BTU room AC and and ducting it into that electrical area of the package unit. Might be real cheap insurance. (And I'm sure you can think of some more reasonable idea.)
@mark robertson I'm not sure if that is a deliberately snarky comment for reasons I don't understand, or if maybe the comment means something completely different that I don't understand. What does describing a probable VFD failure cause have to getting venereal disease?
When something blows up like this, probably the lov voltage got shorted to the high voltage side as a result, and tooks with t whatever is connected to it on the LV side. Nice they tear appart as explode, so you it will catch your eye instantly.. Good job man, seeing a pro in his trade has no price.
Chris you're awesome man! Way to find the problem then find a temporary solution and then come back and fix it totally. Awesome video man keep up the great work
Yo Chris i just wanna say thanx for all your hard work and vigilance bringing us these videos. I enjoy watching you making it a little easier for us new guys. ✊🏽
Whew! The attention it took to follow exactly what you were saying and why was mesmerizing and like running an uphill mile. Exhausted but exhilarating. I felt accomplished by hanging on to the end. Just wonderful hearing your mind work. Great job.
Good video. I really liked this one and I agree with Russell's comment. I wouldn't know what to charge for a type of work like this when it takes different trips plus replacing very expansive parts. Thank you again for filming this type of work. It is not easy do film and work at the same time.
Nice video Chris, you covered the entire cooling operation with this call, I would recommend you get a pair of MAGJUMPERS instead of skinning the insulation on the control wires, Thanks for sharing bud !
Small tip from a hvac tech taken a brush and brush the dust from the circuit boards dust can make a short and with the low control voltage that the board needs can give strange problems VFD went due to bad capacitor nice video again Chris
It would of been really nice if that RTU came with a VFD Bypass option! That would of saved you a lot of trouble! I am happy that the customer didn't flip out at you! I hate it when you have to go back to the customer multiple times telling them they are more problems then what was previously quoted? But It's part of the HVAC&R Field! Great Video!
Excellent video! The best advice I've ever received regarding unplugging motherboards (or even doing anything that you're not familiar with) is to take a picture. Unlike the old days, it only takes one high resolution picture and you can zoom in on whatever pin, plug, bolt, etc that you want. For mechanical disassembly, I remove like bolts and group them in a line based on assembly stage. If one stage has two or more sizes, mark each length with a dot matching its corresponding location. It's like a car engine, each piston is marked to belong in a specific cylinder.
19:33 And that right there is likely what killed the old VFD... It got dirty, overheated and went BANG! These things really need to be cleaned regularly, once every 6 months just isn't going to cut it. Clean them every 4-6 weeks or you'll likely severely reduce their Lifespan...
So funny I dealt with a similar situation today and this somehow this came up on my recommended. We had a open trouble on the FACP. The demo guys cut through a thermostat cable and tripped the control transformer fuse. Good documentation here!
Just like the switchmode power supplies to which they're very closely related, the active components in those VFDs have almost no tolerance for errors in their controlling circuits. I'm always fearful of those sprinkler heads when pulling network cables and putting up wireless APs, that some absent minded movement is going to trigger a major disaster through the whole building.
Matt ,right ? You are inspiring me . Really ! I have been leaving comments left and right on alot of your video's. I only wish I found you awhile ago. Thank you for your time . It must be distracting troubleshooting and shooting a video.
I see taking a picture with your phone of the elect control panel helps to make sure the connectors go back in the proper place?? I hope you have a employee with you so he can learn from what you are doing. You are doing so really good troubleshooting right now. Nothing like hands on training for the troops.
Great video amazing how complicated these units can get to meet energy consumption requirements. I’m an electrician and what I find odd is the fire alarm supervisory circuit should not be dependent on the units power supply, the supervisory power should come from the fire alarm panel/sub panel and should just monitor the continuity of the alarm wires and the smoke detector it shouldn’t matter if the unit has power or not to cause a supervisory alarm. I think you may have had a surge on the system power side that may have damaged the board maybe that unit was the closest to the surge is why it was the only one effected. Just my two cents, great video and great service skills to get that unit working temporarily.
I'm a Chef by trade and Love your channel because I can relate to a lot of the crap that gets dealt your way. I've noticed on this Lennox unit and maybe another... The Compressors are in the "Electrical Compartment" of these units not out by the Condenser. I would think they would need air for cooling of the compressor. Do they generate that little heat or does the refrigerant absorb heat from the compressor ? Like reach ins, walk ins, Cold Tables... the compressors are generally right in line or offset of the fan pulling air through the compressor. Thorough meticulous repair as always.
On the job training for this side of the camera, thanks for sharing. Oh, and thanks for the promo code as my Fieldpiece should arrive around the 13th or so. Cheers
As for the VFD, the caps are swollen, common problem over time and with heat, dirty fan would indicate that's a possibility. The destruction can also happen in startup when the spare VFD has been on the shelf for a long time (years) and the caps lose their polarity. You have to "reform" them with a slow introduction of the supply voltage. That is far less common but it worth knowing about. Another advantage of the VFD is that they don't care about the phase rotation.
Who complains about calling tech support?? I was on the phone with them at least twice a week! Calling tech support is not a sign of weakness or that you don't know what you're doing, but it's always nice to have another brain working with you that specializes in a specific product.
You're great man i learn lot of you thank you for your videos i hope my skill and technical experience it's getting more improvement to learn kind of this jobs and ideas, keep it up my friend.
You are a lucky man. We had a technician pop one while replacing a water heater on the 7 floor. Costly mistake, They should have it replaced to be safe. Don't want that sucker popping after hours.
I don't know if you (or anyone) will ever be in this situation again, but it looks like the D700 series is able to have a minimum frequency programmed in relatively simply, so instead of reinstalling the contactor while you waited for the board to be ordered, you possibly could have set a minimum frequency for the VFD which could have saved some installation time.
Great job, I have learned from you something about VFD troubleshooting and how to jumper it out ( temporarily) … Thank you for that, I would really like to know how you discovered or recognized the two control wires that should be hooked up to the contractor’s coil ?
i dont know if anyone seen but at 12:12 just above the blue wire with the yellow connector on the contacter, there is a spark i only seen it that time and no other time
There is nothing wrong with calling tech support, it can save you a lot time and some headaches too. An Another great video and showing sometimes jobs are more involved.
In that situation, with 2 other identical units on the roof, I very carefully swap boards to see which board is bad. But, you really gotta be careful not to screw up. Lennox had/has great tech support. I’d call them in a heart beat. Slowing the fan down de-humidifies much better as coil is colder. Thanks.
Often times when changing dense boards like that, I will write with a fine point sharpie on the flying connector the number of the mating connector on the PCB. Taking a few pictures from different angles is also a big time saver.
I'm gonna be honest, I'm only 15 and no one in my family works in HVACR, and i have no idea how i found your channel. I am so glad that i did find your channel, your videos are just so interesting! I hope we could eventually meet in real life!
Feels like those VFD drives should just have versions with more fans and changeable filters. That way they don't get as dusty inside and should last a lot longer. For this application having them be very compact doesn't matter. Maybe have an attachable intake fan + filter? But that would reduce sales for the VFD guys so... not sure if that would happen ... also maybe that use is too niche for those drives?
Without watching the entire video yet, did younsee the spark arcing when the contactor pulled in? It is at around 12:15. Also, why didn't you show you removing the balloon from the air intake?
Sunscreen, don't leave the home without it or forgot to wear it. Landscape gardener here, spending +12-14 hours outside in all weather. Raincoat is good too, maybe a packet of single use poncho's, a pair of wellies (if you're british/rain boots if you're 'Murican) because wet socks sucks.
Whenever You Are Changing the Air Filters Those vfd's & circuit boards Need Blown out with Dry nitrogen too. I Have 2 - 50' - 1/4" Yellow Refrigerant Hoses that i use. Air hose can work too. I use the same hoses to Fill the Tires on my truck.
Why the hell do these units have no fuses for just about anything? Normally there would be fuses or breakers for the drive, motors etc. Looks like electrical regulations in the US are really lax about this. No surprise the VFD fails that way. When these blow here, even with 400V mains, the input fuse blows and there isnt any damage beyond the power module and it usually can be repaired.
@Timothy Salomon Idk about HVAC, in my field of industry, we frequently have to deal with really old, hard to replace parts and often go for component level repair, sometimes going as far as to qualify as re-engineering.
Fuses are about protecting the wire. In this case, I doubt if any amount of fusing would help much. The protection circuit has to allow enough energy to run the fans - which is more than enough energy to go "bang".
Kind of looks like the VFD IS the fuse. Why sell a $5 fuse, when you can sell a $50 VFD . Or whatever the acctual prices are. I just pulled those numbers out of the air.
When you pulled the VFD, take note of the capacitors. They were severely bulged. Toss it. Electrolytic caps have paste inside. When that paste dries out, kabllooey.
The environment for electronics in a unit like that is terrible, comparable to an automobile. High heat, very cold in winter, vibration and lots of dirt. Not to mention lots of big motors being stopped and started, causing power line transients. VFDs are now everywhere, clothes washing machines, garage openers, residential A/C.
Even fridges got VFD's in them now. Pretty cool (no pun intended), I can never hear my fridge running under normal circumstances. Only time I can hear it very low, is if it has been powered off, or a lot of new stuff has been put into it.
Drives don't care about cold except maybe condensing water. However, in the heat you need to derate those drives. I would have gone up a larger drive if that was the second one blown. We use a lot of those Mitsubishi drives and I've never seen one fail like that. Surprised that if they are only using two speeds they would go through the trouble of a variable output. Just set the two different speeds and use the RH and RM input to select.
All those small gauge wires in the top "half" of the drive are I/O. Inputs are configured to cause the drive to do something, ie. change speed, run stop or jog etc. Those would come from the main controller. The outputs are configured to tell the controller that something has happened, ie. the drive has failed or the motor is running etc. When we install a drive in our equipment {not HVAC} we either download a parameter file {for large parameter changes} or manually change some parameters. We just had a case where we installed a motor/drive combo and the motor was drawing twice it's rated current with minimal load. Turns out that the motor inductance parameter got changed somehow. We determined a close value for that parameter and now the motor draws a little less than nameplate.
I work on a lot of Lennox units and I haven’t ran into a Lennox unit that didn’t have a blower motor contactor to by pass the VFD incase it took a shit. Majority of the drives I see are inside by the blower motor.
Great video this is what happen when the manufacturer over engineering their product . Chris hope they put in a Aegis ring on the blower motor it protects the motor bearing from the VFD.
Great videos... still looking for a compressor autopsy .. what is the life cycle on these units you replace. 5 years? Really need to see the inside.. thanks
Could have a brownout. Had a store where I was constantly replacing burned out 24 coil contactors on the a.c.. It turned out the feed lines to the store in the ground were effed up.
I think VFDs are great when they're of good quality and properly installed. They allow you to do so much with just one motor. Low demand or a need for de-humidification? Low and slow... High demand? Full speed ahead! You can maintain static pressure or airflow based on feedback... the options are endless. VFDs typically are set up with 3 I/Os. start/stop, analog speed (or in this case a pre-programmed 2nd speed), and a dry contact for alarm. Of course you can configure a lot more I/Os for other things as well. The better units can be configured for a lot more. Alas, here you see what seems to be a poor implementation. 3 compressors and other equipment sharing the same space on a roof that can reach extreme temps, baking in the sun. Sounds like a recipe for disaster if I've ever seen one.
Wonder if you fixed RTU 1 and removed the balloon . I had a AAon was running no ac ,had to dust off dust and dirt off gas mod board , must have back feeding voltage to control board , Have you ever worked on a AAon unit? There easy to check and trouble shoot ,just need to have the hand controller the owner should have this if they have this style of unit ,we have 13 unit at our Nursing Home.
If you expect that a system has no power it's actually better to use the NCV function of the multimeter, additionally to checking AC voltage with the leads. It makes sure there's no backfeed from a different circuit you didn't expect.
As an electronics tech, something that caught my eye was that line of dirt on the bottom of the main board. Dirt can become conductive, especially when the humidity rises and then you'll get all kinds of weird problems. Just part of how I roll when it comes to big picture, inspecting, and doing it right. I use an acid brush that I've cut the bristles to half length to stiffen them. That and a vacuum cleaner.
I know absolutely nothing about HVAC. I have no idea why TH-cam recommended this channel but I'm glad they did. I have no idea why this is so entertaining. I think it's the way you explain things so well. I'm subbing.
Thanks so much!!
Super videos, 50 years in our trade but still learning. I will never forget my instructor so many years ago saying for the first five years you know nothing. Keep safe.
I Stand Behind My Work!!! ..... Far Behind... So if it blows up, I Don’t Get Hurt! Thanks for sharing! 👍
The placement of that fire sprinkler by the ladder is just an accident waiting to happen. Great video as always.
And I bet it is mandated by the local fire codes. A sprinkler in the top of a chimney to keep it cool.
l wilton I would’ve expected to see that in his other videos where he shows the roof hatch then.
i have seen one guy got his hat caught in it n set off sprinker ROFL
easy way get away with it put big cup with duck tape on it that way doesnt get caught on something when ya coming up there
Haha, yes, love it! lol each time I saw it in the video just thinking of it and it being caught on video too. I'm glad I didn't choose your trade when I left school but I love watching you doing such an important job in often horrible conditions. Respect to you.
Almost certainly mandated by code - would be here in Aus. So in reality the failure is on the part of the architect providing insufficient space for access (fairly normal from experience) or failing to provide other suitable access -,eg external. That of course brings in a much bigger picture and that has always been the issue with facilities design for engineering services. In the end, it’s the service tech. wearing the problem. I think a cage over the outside of the head would avoid triggering the head but might reduce available space too much. Another two inches on the access and much better!
God bless you for working at so many restaurants, I imagine it’s like pulling teeth at times convincing people they actually need things repaired/replaced
It's the worst thing to come into a fault half way through the fix, stuff's been removed and the bolts have wandered off ..... great to see just that little bit of detail. Makes life so much easier, especially when you've bolts of different lengths.... that's always fun. I've the same issues at work, you can't fix everything first time. Sometimes you get lucky, most times you open up a whole can of worms....... it's why I like my job. It's boring for the most part but there are moments of happiness when I'm sorting problems out.
Hey Chris. Great job and video again. The haters sometimes criticize you for using tech support. But we mechanics don’t know each and every machine. The folks with tech support many times make us look like heroes. When I was in the field; I loved Lennox units. At Emcor when I was there, we took care of a lot of National accounts. Many times it was a hassle to deal with them but bottom line; they put food on my table. Most of the Target stores that I serviced in San Diego county had those Lennox boxcars. I hope that your business is doing excellent. Stay safe and careful out there. Have a great Thursday evening with your family. God bless.
With a proving circuit, you now have 3 possible states:
- Open: wire is broken
- Shorted: Wire melted or detector tripped.
- Supervisory state: All is fine.
How it often work is with a simple resistor. Basically the resistor 'soft short' the wiring at the end of it. If the panel see the resistor, then the wiring is intact. Open then something is broken, and sorted it mean it tripped or the wire shorted/melted.
Some system will use two resitors, one end of line (the first one) plus another series one with the detector. Now you can have 4 states: open, close, EOL resistor or the tripped resistor. Those can therefore detect between the shorted or tripped condition. Those can help to avoid some nuisance alarm due to a nail in the wiring.
One of the best HVAC TH-cam videos ever made... all your HVACR videos are top notch but this was next level. Nice work Chris thanks for making these.
I've been watching your Videos for the past two weeks now, even though I'm not even remotely connected to HVACR I'm an electrical engineer, but I picked up a fair bit and after reading up on some terms that meant nothing to me like superheat etc. I even start to understand how and why you do things. So you do a pretty good job on explaining and methods. Probably will never put that knowledge to any greater use since the HVACR guy at our company didn't even take me serious as I told him that it sounds like a bearing in the compressor is about to die (compressor died 2 Weeks later, took them 3 months to get a new unit installed, industrial carrier cold water circuit, those roof direct air units are very uncommon in europe) but it never hurts to know things outside of your job, so thanks for providing :)
Merch is our way of supporting you and advertising your channel while getting something cool in return love the videos keep it up
Anyone else just enjoy watching him fix stuff?
Nice work Chris. Good job on getting things up and running temporarily with the contactor.
Don’t worry about the sprinkler. I’m a truck driver and had a load to an enclosed strip mall that had a height hog 13’6.5”. My truck is 13’6”. The day before they had lowered the sprinklers 2”. I took off 4 sprinkler heads; it looked like a Roman fountain goin off on the top of my trailer. It was quite scenic.
Not!
As soon as they came out with the first Prodigy, I learned to replace every controller with a new display as well.
Looked up Spec on that VFD (FR-D720-100-NA). It looks border line in it's sizing. It's rated at 10 A up to 122°F. It should have over temp protection. But from all that dirt I see from the cooling fan means the heat sink is most likely dirty. Thus reducing it's cooling capacity. If this is an common issue look at replacing them with the FR-D720-165-NA model. It's rated for 16.5 A.
It's also probably running closer to 150 F ambient mounted in that unit on the top of a roof in So Cal. You can see two of the main filter caps have died, and this was quite likely from the prolonged high temperature soaking. I strongly suspect those caps failing was the root cause of the VFD failure, not a (stupidly) borderline current rating.
@@lwilton Not to mention dirty supply from all the contractors and motors etc in the various AC's etc/ But you are right the caps are not going to like sitting out there in the hot sun all day at 150f/65.55556c. That's going to be a bit hot even for the micro controller inside of the VFD too. I'd go as far as 50% de-rate them, go find one that will supply the required amps after 50% de-rating it.
@@lwilton Seems like a business to re-solder new caps.
i know nothing about hvac at all, but these vids are just very interesting for some reason. keep them coming
Man , this was a good vid Chris ...Love the little Prayers before start-up ...Lol ... Very bourbon worthy ...
Nice job: You can't beat the older style units that have only relays that operate the stages and systems. Sometimes the new tech stuff cost more that it saves. Thanks for the video.
Waterman one Watching this video was fascinating, but also a infuriating. Why so complex? KISS...
@@gordonrichardson2972 thank our "environmentalist" buddies. Don't get me wrong - I'm all for conservation. But how about conservation with some common sense that's not completely divorced from reality?
@@ItsMrAssholeToYou 👍. Agreed.
Yeah. I'm not in the industry, but I have to wonder if that VFD and all the circuitry that controls it is really more economical than a two speed motor controlled by relays and contactors.
@Sean That is throwing the baby out with the bathwater. Nothing wrong with using chips and such where it makes sense. It just doesn't make sense to use them for ~5% energy savings while sacrificing ~25% in the reliability.
Thank you, for this video. I have not seen these here in Michigan, yet, but given the energy regulations and the closing of coal fired plants, it's only a matter of time before I have to deal with these VFDs. Thanks to you, and your experience, I will have a leg up. Thank You.
Real electrical engineers know how to do multi-speed motors with no electronics. This gratuitous electronic is being put in there simply to generate service calls. True variable speed units like the mini-splits I installed in my retirement cabin are a different matter. Even then the chicoms are running the power transistors at absolute max rating which is why one driver board has already failed.
suggestion: When filming the prodigy boards - try using a slightly longer shutter time (in most phone models if you use a phone to film - have a "advanced" or "pro" mode to set shutter). You might need to reduce apeture tough. If your phone or camera allows saving profile, try getting a good profile for just prodigy boards, and then save it as 2 profiles, one for "normal" filmning and one for "prodigy". Play around with the camera settings - should be pretty easy if you have a prodigy board at home, until you get a nice view.
Usually wouldn't work as the outdoor sun is too bright for a slower shutter speed. We use ND filters for that, but finding one for phone cameras might be difficult. An easier way might be to just put sunglasses / welding goggles in front of the camera and let the auto exposure adjust.
That opening clip... I cringed so hard. Brought back memories of working in a certain home improvement chain's local distribution center. A sprinkler head was RIGHT next to the warehouse racks, and there were many than occasions where we had to shut down and evacuate because someone on powered equipment had taken off the head and triggered the fire alarm. I kept suggesting to anyone that would listen that we should install a small cage of rebar around it to protect it from impact, but nobody cares what the fireman's son has to say about the fire alarm system.
OOOF, those exploded capacitors on the VFD are definitely the cause of the tripped breaker! I wonder if they failed due to high temperatures on the roof? High temps cause the dielectric to breakdown and the caps then basically become shorts. Mitsubishi also had an issue with bad capacitors in some of their cars' ECMs in the '90s because they used a cheaper brand instead of their own parts - they dried out under the harsh temperatures inside a car and failed. As you said, putting the VFDs in a cooler environment will extend their lifespan. Judging by the incredible scorch marks inside the dead VFD, I guarantee some HV arced over to the LV sections, if I had to offer a theory (much simpler, but similar to I wilton's theory) the faulty caps became dead short, high voltage arced to low voltage sections, and from there basically grenaded the daughter board and probably parts of the main board.
Great customer service !!
Pretty fair guess about what happened to that unit:
Looking at the VFD innards, it is immediately obvious that two of the main filter caps have failed. Others may have also failed, but those two probably were enough. They were probably bad enough that they were supplying AC to the VFD logic when it should have been DC.
This probably wouldn't have damaged the chips, but it trashed their operation, and they got completely confused. Somewhere in their confusion, they turned on two or maybe all three phases at once, shorting the line across the power MOSFETs in the driver part of the board.
The result was a lot of black greasy smoke and shrapnel all over the inside of the VFD. A lot of nice greasy conductive smoke, probably along with a nice hot arc for a very short time. Probably the arc migrated from the power MOSFETs into the logic chips. From there it fed back along the control lines and momentarily put 208 onto the logic of the main control board.
The VFD control may be partially isolated, but not enough so. The short pulse of HV didn't completely smoke the control, but it was enough to confuse the heck out of it, and possibly fry some logic as well as wiping out the flash/EEPROM memory in the unit.
You are probably right that having that VFD in a more climate controlled room would have preserved it. I suspect if you put a recording thermometer in the VFD case you would find that it is way over the max continuous operating temperature for a good part of the day in summer.
I'm not an air conditioning guy, so I might seriously consider going to Lowes and getting a 5000 BTU room AC and and ducting it into that electrical area of the package unit. Might be real cheap insurance. (And I'm sure you can think of some more reasonable idea.)
The better designed units have a hole to leak a small amount of conditioned air through the controls compartment during operation.
@@zjeepgozweeln a little suggestion put the vfd in the blower compartment it's colder
Joel Acosta then you run into Condensation issues with the VFD.
@mark robertson I'm not sure if that is a deliberately snarky comment for reasons I don't understand, or if maybe the comment means something completely different that I don't understand. What does describing a probable VFD failure cause have to getting venereal disease?
When something blows up like this, probably the lov voltage got shorted to the high voltage side as a result, and tooks with t whatever is connected to it on the LV side. Nice they tear appart as explode, so you it will catch your eye instantly.. Good job man, seeing a pro in his trade has no price.
Chris you're awesome man! Way to find the problem then find a temporary solution and then come back and fix it totally. Awesome video man keep up the great work
Yo Chris i just wanna say thanx for all your hard work and vigilance bringing us these videos. I enjoy watching you making it a little easier for us new guys. ✊🏽
Whew! The attention it took to follow exactly what you were saying and why was mesmerizing and like running an uphill mile. Exhausted but exhilarating. I felt accomplished by hanging on to the end. Just wonderful hearing your mind work. Great job.
“Im not perfect I don’t always get it on the first call...it is what it is..” man I appreciate the realness.
“stand back man” lol, made me feel like I was there on the roof with you,
How enjoyable is watching your videos ! I love see people passionate doing their job, motivate us ! Great videos 👏🏻👏🏻👏🏻
Good video. I really liked this one and I agree with Russell's comment. I wouldn't know what to charge for a type of work like this when it takes different trips plus replacing very expansive parts. Thank you again for filming this type of work. It is not easy do film and work at the same time.
Who in the hell put a sprinkler right in the way of the ladder to the roof excellent work and thanks for the awesome content stay safe and take care
Nice video Chris, you covered the entire cooling operation with this call, I would recommend you get a pair of MAGJUMPERS instead of skinning the insulation on the control wires, Thanks for sharing bud !
Small tip from a hvac tech taken a brush and brush the dust from the circuit boards dust can make a short and with the low control voltage that the board needs can give strange problems VFD went due to bad capacitor nice video again Chris
It would of been really nice if that RTU came with a VFD Bypass option! That would of saved you a lot of trouble! I am happy that the customer didn't flip out at you! I hate it when you have to go back to the customer multiple times telling them they are more problems then what was previously quoted? But It's part of the HVAC&R Field! Great Video!
I greatly appreciate your humility but you are incredible!
Excellent video! The best advice I've ever received regarding unplugging motherboards (or even doing anything that you're not familiar with) is to take a picture. Unlike the old days, it only takes one high resolution picture and you can zoom in on whatever pin, plug, bolt, etc that you want. For mechanical disassembly, I remove like bolts and group them in a line based on assembly stage. If one stage has two or more sizes, mark each length with a dot matching its corresponding location. It's like a car engine, each piston is marked to belong in a specific cylinder.
19:33 And that right there is likely what killed the old VFD...
It got dirty, overheated and went BANG!
These things really need to be cleaned regularly, once every 6 months just isn't going to cut it.
Clean them every 4-6 weeks or you'll likely severely reduce their Lifespan...
So funny I dealt with a similar situation today and this somehow this came up on my recommended. We had a open trouble on the FACP. The demo guys cut through a thermostat cable and tripped the control transformer fuse. Good documentation here!
Great content you explaining the sequence of operations and the idea behind the VFD. Thank you.
I always get some new knowledge from your videos! A good tech will never stop learning. Thanks for the great video as always.
You get a like before I watched the whole video. That says so much about me LOVING your videos!
Just like the switchmode power supplies to which they're very closely related, the active components in those VFDs have almost no tolerance for errors in their controlling circuits.
I'm always fearful of those sprinkler heads when pulling network cables and putting up wireless APs, that some absent minded movement is going to trigger a major disaster through the whole building.
Matt ,right ? You are inspiring me .
Really ! I have been leaving comments left and right on alot of your video's.
I only wish I found you awhile ago.
Thank you for your time . It must be distracting troubleshooting and shooting a video.
I see taking a picture with your phone of the elect control panel helps to make sure the connectors go back in the proper place?? I hope you have a employee with you so he can learn from what you are doing. You are doing so really good troubleshooting right now. Nothing like hands on training for the troops.
Wow that view is amazing! I live in Southern Illinois and of course we have nothing like it. Thanks for the video and the wonderful view.
Nothing like a 9,000 foot high mountain range 5 miles away to improve the view! :-)
I'm going to pay to put up a bunch of upside-down billboards in Chris' service area and watch him slowly slip into madness.
Great video amazing how complicated these units can get to meet energy consumption requirements. I’m an electrician and what I find odd is the fire alarm supervisory circuit should not be dependent on the units power supply, the supervisory power should come from the fire alarm panel/sub panel and should just monitor the continuity of the alarm wires and the smoke detector it shouldn’t matter if the unit has power or not to cause a supervisory alarm. I think you may have had a surge on the system power side that may have damaged the board maybe that unit was the closest to the surge is why it was the only one effected. Just my two cents, great video and great service skills to get that unit working temporarily.
That's a nice rooftop!
Remember this place where the main exhaust fan was replaced?
Yep
I'm a Chef by trade and Love your channel because I can relate to a lot of the crap that gets dealt your way. I've noticed on this Lennox unit and maybe another... The Compressors are in the "Electrical Compartment" of these units not out by the Condenser. I would think they would need air for cooling of the compressor. Do they generate that little heat or does the refrigerant absorb heat from the compressor ? Like reach ins, walk ins, Cold Tables... the compressors are generally right in line or offset of the fan pulling air through the compressor. Thorough meticulous repair as always.
The compressor is cooled by the returning refeigerant and that heat is rejected out the condenser
@@HVACRVIDEOS Thanks !!! Kind of thought that but wasn't sure.
On the job training for this side of the camera, thanks for sharing.
Oh, and thanks for the promo code as my Fieldpiece should arrive around the 13th or so.
Cheers
As for the VFD, the caps are swollen, common problem over time and with heat, dirty fan would indicate that's a possibility. The destruction can also happen in startup when the spare VFD has been on the shelf for a long time (years) and the caps lose their polarity. You have to "reform" them with a slow introduction of the supply voltage. That is far less common but it worth knowing about. Another advantage of the VFD is that they don't care about the phase rotation.
I agree that is a stupid spot for a sprinkler
That is an insane sprinkler head placement.
Who complains about calling tech support?? I was on the phone with them at least twice a week! Calling tech support is not a sign of weakness or that you don't know what you're doing, but it's always nice to have another brain working with you that specializes in a specific product.
Thank you for the video. The company Forgot about maintenance. the new Units Have More Electronics Parts the require maintenance.
You're great man i learn lot of you thank you for your videos i hope my skill and technical experience it's getting more improvement to learn kind of this jobs and ideas, keep it up my friend.
You are a lucky man. We had a technician pop one while replacing a water heater on the 7 floor. Costly mistake, They should have it replaced to be safe. Don't want that sucker popping after hours.
That skyline backdrop is amazing. even with a huge ac in the frame.
I don't know if you (or anyone) will ever be in this situation again, but it looks like the D700 series is able to have a minimum frequency programmed in relatively simply, so instead of reinstalling the contactor while you waited for the board to be ordered, you possibly could have set a minimum frequency for the VFD which could have saved some installation time.
Great job, I have learned from you something about VFD troubleshooting and how to jumper it out ( temporarily) … Thank you for that, I would really like to know how you discovered or recognized the two control wires that should be hooked up to the contractor’s coil ?
i dont know if anyone seen but at 12:12 just above the blue wire with the yellow connector on the contacter, there is a spark i only seen it that time and no other time
There is nothing wrong with calling tech support, it can save you a lot time and some headaches too. An Another great video and showing sometimes jobs are more involved.
Ghosh! Ur experience is great wish i worked with U.God Bless.
again, great entertaining yet educational video
You're the difference between a "Mechanic" and a Swapologist ...Nice to see someone that knows their job and does it well...:)...
In that situation, with 2 other identical units on the roof, I very carefully swap boards to see which board is bad. But, you really gotta be careful not to screw up. Lennox had/has great tech support. I’d call them in a heart beat. Slowing the fan down de-humidifies much better as coil is colder. Thanks.
Those black electrolytic capacitors in the VFD are toast! - see how puffy they are?
Often times when changing dense boards like that, I will write with a fine point sharpie on the flying connector the number of the mating connector on the PCB. Taking a few pictures from different angles is also a big time saver.
Can u do a video on vfd. Your videos are very good and helpful. I have been on the refrigeration side and now find myself on the ac side due to covid.
I'm gonna be honest, I'm only 15 and no one in my family works in HVACR, and i have no idea how i found your channel. I am so glad that i did find your channel, your videos are just so interesting! I hope we could eventually meet in real life!
I'm 38 it blows my mind...your young though.....he will point you in right direction...
Feels like those VFD drives should just have versions with more fans and changeable filters.
That way they don't get as dusty inside and should last a lot longer.
For this application having them be very compact doesn't matter.
Maybe have an attachable intake fan + filter?
But that would reduce sales for the VFD guys so... not sure if that would happen ... also maybe that use is too niche for those drives?
it is interesting, I don't think I have ever seen a running VFD that was not full of dust.
I didn't understand anything but i watched it all. Nice video. Looks like you are a Pro 👍.
Cant wait to get the shirt. Keep it going
Without watching the entire video yet, did younsee the spark arcing when the contactor pulled in? It is at around 12:15. Also, why didn't you show you removing the balloon from the air intake?
Great troubleshooting skills
Awesome video always it's very accurate ...👍👍❤❤...watching from Philippines
Sunscreen, don't leave the home without it or forgot to wear it.
Landscape gardener here, spending +12-14 hours outside in all weather.
Raincoat is good too, maybe a packet of single use poncho's, a pair of wellies (if you're british/rain boots if you're 'Murican) because wet socks sucks.
Whenever You Are Changing the Air Filters Those vfd's & circuit boards Need Blown out with Dry nitrogen too. I Have 2 - 50' - 1/4" Yellow Refrigerant Hoses that i use. Air hose can work too. I use the same hoses to Fill the Tires on my truck.
Dry nitrogen isn't needed for that. Ordinary compressed air passed through a dryer is more than adequate.
Very informative video thanks
Why the hell do these units have no fuses for just about anything? Normally there would be fuses or breakers for the drive, motors etc.
Looks like electrical regulations in the US are really lax about this. No surprise the VFD fails that way. When these blow here, even with 400V mains, the input fuse blows and there isnt any damage beyond the power module and it usually can be repaired.
it should have also a self protection cyrcuit.. was a mitzubishi if i didnt see wrong.. how can fail so badly?
@@riccardoz2953 Normally VFDs dont have any internal fusing and require external, properly sized, current limiting, fuses.
@Timothy Salomon Idk about HVAC, in my field of industry, we frequently have to deal with really old, hard to replace parts and often go for component level repair, sometimes going as far as to qualify as re-engineering.
Fuses are about protecting the wire. In this case, I doubt if any amount of fusing would help much. The protection circuit has to allow enough energy to run the fans - which is more than enough energy to go "bang".
Kind of looks like the VFD IS the fuse. Why sell a $5 fuse, when you can sell a $50 VFD . Or whatever the acctual prices are. I just pulled those numbers out of the air.
You did good Bud.
When you pulled the VFD, take note of the capacitors. They were severely bulged. Toss it. Electrolytic caps have paste inside. When that paste dries out, kabllooey.
Or find replacement capacitors and re-solder new ones. Same thing happened to motherboards back in the day.
I’m just curious, when you were looking for 24v to energize the contactor, couldn’t you get it from common and G off the terminal port?
The environment for electronics in a unit like that is terrible, comparable to an automobile. High heat, very cold in winter, vibration and lots of dirt. Not to mention lots of big motors being stopped and started, causing power line transients. VFDs are now everywhere, clothes washing machines, garage openers, residential A/C.
Even fridges got VFD's in them now. Pretty cool (no pun intended), I can never hear my fridge running under normal circumstances. Only time I can hear it very low, is if it has been powered off, or a lot of new stuff has been put into it.
On the bright side, the epoxy (?) coating on the new M2 seems thicker which should help a bit.
Most units have vent holes that keep that compartment warm, some times
Drives don't care about cold except maybe condensing water. However, in the heat you need to derate those drives. I would have gone up a larger drive if that was the second one blown. We use a lot of those Mitsubishi drives and I've never seen one fail like that.
Surprised that if they are only using two speeds they would go through the trouble of a variable output. Just set the two different speeds and use the RH and RM input to select.
Stupid to have a VFD at 59hz. It should just bypass at that point, run at 60hz and let the VFD electronics take a rest.
All those small gauge wires in the top "half" of the drive are I/O. Inputs are configured to cause the drive to do something, ie. change speed, run stop or jog etc. Those would come from the main controller. The outputs are configured to tell the controller that something has happened, ie. the drive has failed or the motor is running etc. When we install a drive in our equipment {not HVAC} we either download a parameter file {for large parameter changes} or manually change some parameters. We just had a case where we installed a motor/drive combo and the motor was drawing twice it's rated current with minimal load. Turns out that the motor inductance parameter got changed somehow. We determined a close value for that parameter and now the motor draws a little less than nameplate.
I work on a lot of Lennox units and I haven’t ran into a Lennox unit that didn’t have a blower motor contactor to by pass the VFD incase it took a shit. Majority of the drives I see are inside by the blower motor.
Well that was I interesting, the VFD adds a few challenges. But now you know what to look for next time they fail.
Great video this is what happen when the manufacturer over engineering their product . Chris hope they put in a Aegis ring on the blower motor it protects the motor bearing from the VFD.
Good vid. That was a Pain in the backside job. Holy smokes.
Impact rated/bashable screw drivers are the #1 tool in any tool bag.
Great videos... still looking for a compressor autopsy .. what is the life cycle on these units you replace. 5 years? Really need to see the inside.. thanks
Could have a brownout. Had a store where I was constantly replacing burned out 24 coil contactors on the a.c.. It turned out the feed lines to the store in the ground were effed up.
Great job again like always and great video
I think VFDs are great when they're of good quality and properly installed. They allow you to do so much with just one motor. Low demand or a need for de-humidification? Low and slow... High demand? Full speed ahead! You can maintain static pressure or airflow based on feedback... the options are endless.
VFDs typically are set up with 3 I/Os. start/stop, analog speed (or in this case a pre-programmed 2nd speed), and a dry contact for alarm. Of course you can configure a lot more I/Os for other things as well. The better units can be configured for a lot more.
Alas, here you see what seems to be a poor implementation. 3 compressors and other equipment sharing the same space on a roof that can reach extreme temps, baking in the sun. Sounds like a recipe for disaster if I've ever seen one.
zjeepgozweeln Fine summary of a waste of good technology!?
Wonder if you fixed RTU 1 and removed the balloon . I had a AAon was running no ac ,had to dust off dust and dirt off gas mod board , must have back feeding voltage to control board , Have you ever worked on a AAon unit?
There easy to check and trouble shoot ,just need to have the hand controller the owner should have this if they have this style of unit ,we have 13 unit at our Nursing Home.
Yes
If you expect that a system has no power it's actually better to use the NCV function of the multimeter, additionally to checking AC voltage with the leads. It makes sure there's no backfeed from a different circuit you didn't expect.