Lennox Prodigy Playing Games RTU Not Cooling

This Lennox packaged rooftop unit had a Prodigy 2.0 Unit Controller board that was acting up causing the compressors to short cycle resulting in the main breaker tripping. I have not done a lot of work with the prodigy system so common sense led me to what I found, and I confirmed it with Lennox to verify that was the problem before ordering such an expensive part.
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#hvacrsurvival #hvaclife #hvacservice #hvacr #refrigeration #troubleshooting

[@timbrown9305]

Great to see "REAL" diagnosis. Fantastic !

[@HVACRSurvival]

Thanks 🙏 👍👍

[@matthewrichardson2467]

Hey Rick, Love your methodical troubleshooting approach, and your take the previous guys assessment with a pinch of salt and you confirm things for yourself.

[@gordonborsboom7460]

Satturation temps are the ssame yes...just dont forget to reset the refridgerant type on your electronic gauges. This has caused me all kinds of unnecessary grief

[@HVACRSurvival]

I know me too🤣🫶 it happens all the time

[@jasonyeager9102]

Same…was working on a walk in freezer (404) on one call and then went to a 410A AC call and was like damn this is low…good thing I noticed before going further.

[@ryanisaacson118]

Yep

[@Boodieman72]

Had a local tech come out to do an AC check on my home. Somehow they managed to short or do something that killed both the circuit board and the wall thermostat. Nice to see a real professional at work.

[@HVACRSurvival]

That really sucks, sorry to hear that! Thanks for checking out the video!

[@TheGhettoLobster]

They hooked up the high voltage to the low voltage on the contactor

[@jasonjohnsonHVAC]

Nicely done Rick. Condemning a board is the absolute last thing on my list, whether i originally suspected it or not. You were very detailed and methodical in your approach

[@HVACRSurvival]

Cool, thanks! I knew that control board was going to be pretty expensive so I want to be darn sure.

[@jasonjohnsonHVAC]

@HVACRSurvival and you did make sure. Too many people condemn a board without going through the proper steps.

[@jaymartin5095]

I had been wondering where you were. Thanks for the update. This one was interesting, eliminating everything else one by one. Then have the vendor confirm it's their board. Nice sleuthing and keeping your cool. Thanks for the education.

[@HVACRSurvival]

Thanks Jay! Yep just stupid busy

[@stevencossaboon3237]

Nice troubleshooting and job Rick.

[@Josh.SPublishingTeam2024O]

Good video rick from watching your videos i learn alot about these units! 🎉🎉

[@HVACRSurvival]

Thanks Josh!

[@throttlebottle5906]

"how dare you" not release videos daily. LOL. I was ready to send search and rescue looking for the roof, rack or cooler you was stuck in. 🤣🤣🙃

[@HVACRSurvival]

🤝😅👍👍

[@zekenzy6486]

Great video. Thank you for sharing. Have a nice weekend. I'm so happy to see you back. I see you in next video 💯

[@HVACRSurvival]

Thank you, I’m gonna try for another tomorrow but it depends on time

[@jimfurnell7657]

Awesome diagnosis' your trouble shooting skills really make me stop and rethink of my approach to low voltage issues. Sometimes they can drive a us techs crazy. Great informative videos, stay safe.

[@HVACRSurvival]

Thanks Jim!

[@Boraxo]

That Jumper King is slick. 👍

[@andyread4332]

Love your work Rick. Keep em coming

[@HVACRSurvival]

Than you!

[@Dalan612]

Solid troubleshooting Rick. Thanks for the upload 🤘🏼

[@HVACRSurvival]

No problem 👍

[@johnstrh1]

any other newer guys like me watching, what he said about looking at the temps not the pressures is what really helped me a while ago. when you see 5 or 6 different refrigerants in a day going by temp is so much easier

[@HVACRSurvival]

Preach it 🙌

[@Brooks.Mechanical.Electric]

It makes so much more sense than trying to memorize pressure for everything you work on. I learned that way and rarely even put much though in the pressures.

[@HVACRSurvival]

@Brooks.Mechanical.Electric It just clicked for me early on. It’s amazing how much you hear about pressure when listening to others.

[@Brooks.Mechanical.Electric]

@@HVACRSurvival went back this evening and looked up some of your old videos on geo units and found where you showed your gauge setup. Where would I find the needle end to adapt to the test port?

[@HVACRSurvival]

@Brooks.Mechanical.Electric you can find it online if you search for geothermal suppliers I was able to get mine at my carrier supply house. Habegger Corporation is who we use.

[@thesilentonevictor]

Good troubleshooting Rick

[@helmsajr]

Great job Rick Lennox not my favorite unit to work on but you got it figure out.

[@HVACRSurvival]

Thanks 👍

[@LilyRoseElectric]

Great job 👏 Killing it.... always the best

[@kenebler7855]

Awesome video thanks for going through everything like you did very helpful

[@HVACRSurvival]

No problem 👍

[@wd8557]

Nice, I'll have to put this one down in my book.

[@user-bj3wj9oj6h]

Thanks for your videos.

[@HVACRSurvival]

Glad you like them!

[@maintenanceman1015]

Worked on AAON units where the control board controlled a bank of relays . If a contractor went bad it couldn`t take out the main board. But had the blower short cycle ,the relay would turn on the Frequency Drive then shut off . Was the coldest day in winter ,why not think was -10 ,just pulled the relay out and reinstalled it . Good to go , Got 3 back relays just in case , 13 AAON units at that location.

[@elBusDriverKC]

On those prodigy units, they have a self test mode. Pulling the wires from the thermostat connections and putting it into self test can help get thermostat problems / thermostat wiring problems out of the picture. I've seen a few go bad here and there. At $750 - $1000 it's an expensive failure. Fun part is having to reprogram the new controller for all the fancy settings.

[@joeyf504327]

it's probably a failed capacitor on the controller that is there to supply current during DC power draws for the computer when activating the 24VAC control relays. I have seen this happen in printers. They get stuck constantly rebooting because a capacitor fails and can't provide current during startup when there is a momentary power draw. New cap and good to go.

[@HVACRSurvival]

Lennox guy said there’s a relay that fails?

[@kingwookie7210]

lennox one of my least favorite over engineered RTU's, good work as always.

[@HVACRSurvival]

Same here!

[@davidpetetsen3744]

Nice video I had same issues with lennox 25 ton rtu just like that

[@HVACRSurvival]

Good to know I’m not alone

[@Brooks.Mechanical.Electric]

Hey Rick, another great video as always. I've been spending every spare minute i can, which isn't much time these days cramming in all the knowledge I can on the newer equipment we're see on a more day to day basis and one thing I'm having to study up on is geo water sourced units, and ive been doing a ton of inverter type heat pump systems. I know you have a few videos I've watched on the geo / water source systems and was wondering if you have any recommendations for a good pressure gauge for checking out the water loop? Not a ton of info online that ive seen and I thought of you as a good person to ask. Take care my friend and thanks for any suggestions you have!

[@HVACRSurvival]

I use an old refrigeration gauge. R22 type, I drilled the restrictor plate at the bottom. It works great

[@Brooks.Mechanical.Electric]

@@HVACRSurvival awesome, thanks for the info.

[@Gcanno]

Thank you .

[@HVACRSurvival]

You bet! 👍

[@MariosACandRefrigeration]

It could have been a sensor or some other thing,unplug everything and reconnect until it shows a problem to isolate,also you can switch 24 volt on transformers in case that one is weak.thanks for sharing.

[@danpresson]

Awesome video

[@HVACRSurvival]

Glad you enjoyed it !

[@terrygrant8126]

You did good friend!....

[@HVACRSurvival]

Thank you!

[@waynetirrell2358]

Great Video! I always looking forward to each one 👍

[@HVACRSurvival]

Glad you like them! Thanks!

[@MegaDesna]

ALARM 82: Means don't worrey "boutit xD XDD

[@HVACRSurvival]

😅

[@jamesashley3827]

Thanks

[@HVACRSurvival]

Your welcome!

[@Eddy63]

Nice troubleshooting as usual ... Are you & Chronic gonna do any more streaming ... They were always fun ... Thx

[@HVACRSurvival]

Eventually. Crazy busy lately

[@DanielGaytan-vl9hw]

The board has a limit on the incoming voltage, any voltage higher that 27v Ac will cause it to lock out or act like that. You need to change the primary voltage tap on the T1 and T18 transformer to lower the secondary voltage.

[@HVACRSurvival]

You would think Lennox tech services would have said something about that. He did tell me that there’s a relay inside the control that has a history of failing. 🤷‍♂️

[@Pippy626]

I love the videos. If you ever need help with editing I can assist. I wouldn’t mind a few longer videos too

[@rjeepster8640]

I would start by putting a thermostat right to the controller to find out if downstairs is causing your issue

[@knockitofff]

0:34 that's a sheave LOL

[@HVACRSurvival]

Whatever🤫 you knew what I meant. 😆

[@subcoolHVAC]

Nice Troubleshooting , thankfully compressors were still good 👍

[@HVACRSurvival]

You got that right!

[@EverythingHVACR]

Saturation, Saturation, Saturation. Nicely done, Rick

[@HVACRSurvival]

Thanks Steve 👍👍

[@BlackAck90]

Still trying to find out where "AcrossT" comes from.

[@ceilingfanmusic6597]

So i have 2 hypophises as to whata going on with that controll bored. 1: the filter caps on the voltage ragulation circut is going out causing the MCU to be unstable to the point that any change on the power rales causes the MCU to reset. 2 one of the relays on the controller has a shorted coil ( the y1 relay) and when the controller trys energyzing the relay it pulls down the supply dc voltage for the controll bored and causes it to restart. Pardon my bad spelling

[@HVACRSurvival]

Lennox tech service told me that there’s a relay inside there that has gone bad so you might be correct

[@xenories]

It looks like something low voltage is shorted and when it wants to turn on it shorts main transformer, the proper diagnostic whould be to unplug everything from the board and connect slowly thing back until it trips. Or just chech resistance on everything low voltage. I dont think its the main board.

[@HVACRSurvival]

Well, like I said, I talked to Lennox tech-support and they said it was the board. Because what I unplugged was all the outputs. Also, if it was a short, the amperage would’ve went up on the transformer. I eliminated that even as a possibility by putting the amp meter on there.

[@HermesVintage]

Any updates on this service call? If the board solved the issue

[@HVACRSurvival]

It just happen Thursday. The store has a HVAC crew that put on a different series controller and it attest has one stage of cooling until the correct board comes in.

[@AErefrigeration]

Give us a 3 hour video

[@paulb4496]

Most Fluke clampmeters don't have an Ohms scale that reads Millions of ohms. If you are testing for a grounded compressor a meter that uses multiple batteries or a 9 volt battery and reads 40 or 60 million ohms will find a grounded winding.

[@HVACRSurvival]

You’re correct, my clamp does 60k ohms max. Generally most shorts are low. If I think I need more resolution I’ll grab my 87V, 117, or my extech megger

[@halverde6373]

Everyday nightmares every service tech is forced to contend with. How much would you be willing to pay anyone to handle that?😰💰🤣

[@MariosACandRefrigeration]

1 pound of extra refrigerant will make those microchanel trip.

[@MrJujubean]

Great trouble shooting video. You outta here controller lol

[@himrfreeze]

In the service mode u can test. Run each compressor and if you jump have to do y g and r and if summer u can leave compressor on in service mode sometime even with faulty board

[@HVACRSurvival]

I need more time with that board. I haven’t had a chance to work with it much.

[@CM-ou4zr]

Wow that's a bad diagnosis from the guy before you. Shorted compressor? What are they smoking in ohio rick

[@HVACRSurvival]

They diagnosed that on another unit not that one. I just misread it but the way they wrote the description kind of sucked, but since they’ll probably watch the video, I have to be careful what I say.🤣

[@MariosACandRefrigeration]

hello Rick.

[@HVACRSurvival]

What’s up!✌️

[@johnwalker890]

Good job Rick, Ghost controller issues is what I call it, I wasn't sure what happened to you?? I thought you were in You Tube jail?? Just kidding, God forbid......

[@HVACRSurvival]

Nope. I mentioned it at the end. Stupid busy and I’m on call

[@johnwalker890]

Well they got the right guy for it....

[@brianjones5935]

ya let me just rip into the insulation lol

[@steveblake8766]

253 thumbs up

[@thefathvacguy6341]

Trane or Lennox....which do I hate more....hmmmm

[@HVACRSurvival]

🤔🤔🤔🤔 the correct answer is…. Both.😅

[@thefathvacguy6341]

@@HVACRSurvival Very true!!! 🤣🤣🤣

[@halverde6373]

The actual problem is it's a Lennox. Similar to Trane. God help all of us that fight against chaos. Glad I made it out alive to retirement. Fond memories but I don't miss it.

[@tysonrojas5477]

Could of megged out compressors and saved time

[@HVACRSurvival]

Yeah, but unless you have a log of what you’ve had in the past, it’s a well-known fact that you can’t just go up there and make a definite guaranteed diagnosis unless it’s really bad short and you can see the super low resistance and the test voltage actually drops. You can have moisture in the system or liquid lane in the compressor and that will give you a low mega meter reading.

[@mitchelljohnston754]

This happened to me, it was one if the 3 fuses