Heat Pump Troubleshooting- Defrost Board Testing and Bypass for Cooling!

[@acservicetechchannel]

Tool List- www.amazon.com/shop/acservicetech Support- www.patreon.com/acservicetech For those that are looking for the tools used in the videos: (Linked Below) Here is the Link for the newer UEI DL479 Multimeter with temp sensor- amzn.to/2jtsUbJ Here is the Link for the newer UEI DL469 Multimeter- amzn.to/2jw4ePJ Here is the Link for the UEI DL389 Multimeter used in the video - amzn.to/2naJr9o Here is the link for the Irwin Wire Stripper/Cutter/Crimper amzn.to/2dGTj2V Here is the link to the Fieldpiece SDMN6 Dual Pressure Testing Manometer with Pump-amzn.to/2jyK5Ka Here is a link for the Supco Magnet Jumpers amzn.to/2gS4h6z Other tool links can be found in the video description section. ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.

[@johncameron2930]

To

[@anthonyfernandez916]

acservicetech where The T1 and Y where those wire come from please help

[@acservicetechchannel]

Anthony, if the unit is not a Ruud, Rheem, Weathermaker then take your y from the air handler and connect this to one of the two wires coming from the safety pressure switches, then take the other wire coming from the safety pressure switches and attach to one of the reversing valve wires and one side of the contactor. Then connect the other side of the contactor and the other wire from the reversing valve and attach this to the c wire from the air handler. This way you keep the safety wires intact. This is just for cooling for a day or two until you get the defrost board back in or switching from use as a heat pump to ac only if the board is bad, thanks

[@anthonyfernandez916]

acservicetech thank you for answering my question been in the industry for one year

[@acservicetechchannel]

Glad to help Anthony!

[@F33Nominal]

As old as this video is, I must say...it is still saving lives over here! My wife noticed the thermostat was out. Oh boy...here we go! Mind you, I am no AC service tech, but just a homeowner with a handy knowledge of the trades. Noticed a fuse blown in the air handler. Let's hope it was a one off and change it. POP again! Looks like we have to chase down an LV short. Pull the thermostat and removed the terminations hoping it was a bad thermostat. Used these wires to isolate the condensor LV wires and found the yellow wire to the condensor to be the faulty one. Tested both cables to the thermostat and the condensor and both are good! There goes the easy fix....now i am in the condensing unit. Found a circuit board and thought it was game over. I started to remove the thermostat wires one by one from the board (which I later identified as a defrost control board), and after blowing through several fuses, I found the yellow wire to blow the fuse everytime it was plugged into the spade terminal. Now I was done...my first assumption was that the defrost board was bad and now we are just going to have to ride out the night in Florida heat with temperatures inside at 80 degrees. My wife and daughter were sleeping so peacefully but sweating as the temperature was rising. As much as i wanted to do something about it, i felt as if my hands were now tied until i can replace the board, but getting through the night was being Did some research looking to buy a new board and stumbled across your video WITHOUT even thinking that bypassing was a temporary option. Although the system was different, the theory behind it all was the same. Needless to say, I was able to fix this for the night due to your in-depth and detailed explanation of what you were doing. We are now at 76 and dropping. To find a new board is the next move. Will my family suffer tonight? No! Thanks to you for the knowledge and direction you provided! Without it, my family would be miserable tonight. That is no longer the case and I thank you again for it!

i hear you man, i just found it now myself it is 2024 jan. but i wish this was a rheem unit, he was showing here. he said that the rheem unit functions different in cool mode that the other mfg, units. So, i am trying to figure out what the rheem units do in the heat mode now, my out door unit is NOT COMING in either heat or cool, but the indoor blower unit is running ok for now.

[@MkShantrul]

I went to tech school for this but went straight into the building maintenance field not working with this everyday so when I do get a chance too I am not always real confident in myself watching your videos helps bring back things I forgot or things I never ran into yet that you only get in the field and repetition of doing this type of work thanks sir.

[@acservicetechchannel]

Thanks msmolik14!

[@jamesblack3429]

I've watched a lot of his videos and they are all on point and very thorough. He doesn't half ass things and take shortcuts. Done properly, great job bud.

[@acservicetechchannel]

Thanks a lot James!

[@rodballen2331]

this is the best hvac channel ive seen so far.

[@acservicetechchannel]

Thanks so much Rod!

[@rodballen2331]

acservicetech im going to school for this and these videos help alot thanks

[@acservicetechchannel]

That's great to hear. I am a high school and adult HVACR teacher and I have had my business for some years now. This field has always treated me and my family very well. Those that ask questions and have initiative will go far.

[@jimmyjean6663]

I am so bless everytime I'm watching your video. You make me a better tech from your teaching.. i pray God for you to continue adding more knowledge to your brain, therefore you can always share to other people.. May God bless you as always...

[@eastboundtrucking]

Thanks!

[@acservicetechchannel]

Thanks so much!

[@teklesenbetgebreamlak7365]

I WOULD Like to say thankyou lam new technicial to the industry but with your video lam getting more confidence now troubleshooting.

[@acservicetechchannel]

That is really great to hear! Thanks!

[@cecillittle4737]

Thanks for the Video. I had 24 vols=ts on the control but not at the contacter. As soon as I touched and moved one of the wires going from the contacter, the contacter engaged and everything started working!!! I cleaned the stake-ons and am hoping for the best. Thx again Cecil from Florida

[@acservicetechchannel]

Thanks

[@neomacchio4692]

Also thank you! For now, thanks to your video I got my AC working in FL 90deg heat. It’s only going to get worse.

[@MannyFontes1968]

Dude, this video is on point with this bypass you did for cooling. Very thorough explanation and in detail...

[@acservicetechchannel]

Thanks Manny, this is just a temporary bypass. If you were to keep it like this for an extended period, make sure to include the pressure switches in series with the 24v hot to the contactor, thanks!

[@MannyFontes1968]

@@acservicetechchannel you're welcome and I need your help again. My neighbors unit is a complete Rheem system and it stopped cooling a few days ago and I tried doing the bypass but it didn't work like yours did. I did find that the reversing valve and the contacter was not getting the 24v from the defrost board but once I jumped it from the red wire to the contacter and disconnected the 24v side of the rev valve, the system started cooling. It worked for about an hour and half to cool the house to the set temp of 77, but it didn't start up again. I haven't looked at it again but i think it's the contacter that didn't close. I ended up reconnecting all the wires to how it was before and just jumped power to the contacter. Also, the common brown wire color coming from the thermostat doesn't work like it should when it gets to the defrost board. You have to switch it to the blue wire for it to work. This doesn't make sense to me since the schematics show the brown wire as the common. Sorry for the long story.

[@acservicetechchannel]

Rheem powers their reversing valve during heating instead of cooling. The one in the video was a carrier one, thanks

[@borshardsd]

Great content. Beautifully timeless. Old or new videos from you guys its the same excellent delivery 👏

[@pinero155]

Just wanted to say thank you for this very informative video, definitely saved me and I appreciate it thanks once again

[@jimmyung3212]

You are the king of hvac channel!!!

[@acservicetechchannel]

I am glad you are enjoying each of the videos jimmy!

[@HfJax]

Totally agreed

[@NDProps]

You just told me everything I needed to know to fix my unit. Thank you so much. Appreciate you.

[@acservicetechchannel]

You are so welcome

[@MarcusHamilton-vk1tt]

This guy is the best period!!!

[@jimmyjean6663]

Good teaching.. Sir, may God bless you with more knowledge as long as you live on this Earth... you help a lots of new tech out there without knowing. Jesus loves for that

[@acservicetechchannel]

May The Lord Bless You Too Jimmy!!!

[@musicjunkiesstudio]

Thank you . Your video really helped me. Thks for doing what you do.

[@acservicetechchannel]

You are so welcome

[@michaelcostello6991]

A wiring diagram would help a lot for newbies. If you had this on the video that you could reference while you work.

[@acservicetechchannel]

Thanks for letting me know Michael!

[@floridascratcher6190]

ameristar reversing valve works like rudd and rheme also. just fyi. great video and great instructions. i like every video you do

[@sharifbyrd1354]

I understand stand the by passing part great video btw

[@acservicedaytona386portora3]

Explained very well, You do a lot for us, thanx for all the videos, you got a lot on your plate,With work and school, and finding time to do videos..good job. I'm still happy with all that you do.

[@acservicetechchannel]

Thank you very much Robert!

[@ronmason5861]

Makin it simple. Thank you

[@jesuscastillo1083]

Why cut wires from reversing valve simply disconnect them from difrost board and attach direct to contractor?

[@contextkey9913]

This was quite helpful. Thank you

[@Pretzel114]

Nice one ACSERVICETECH. I hope I get a chance to work more on heat pumps so i can put this stuff to use. But till then at least I have the knowledge and can be ready. Thanks again

[@acservicetechchannel]

I am sure you will! Thanks

[@soloch69]

Great video like always 🙌🏻🙌🏻🙌🏻🙌🏻

[@divmart8378]

Esse rapaz é o melhor 👏👏👏👏

[@nissangtr5296]

God bless acservtech i will always be your fan

[@acservicetechchannel]

May the Lord Bless you too! Thanks Murtaza!

[@bass3man2u34]

Thank you so much, you videos are great and easy to understand. thank you again so much for sharing your knowledge. you're awesome dude.

[@acservicetechchannel]

Thanks bass3man 2U!

[@alsur272]

Thank you for useful tutorial video ACSERVICETECH, good job!!! Could you add wiring schematic diagram in description of this video. It would be make even more sense.

[@eracismm]

I thought the same, great video Craig.....

[@Froggability]

The de-ice I'm familiar with is so much simpler. On sensing Low temp, just lifts the neutral to: reversing valve, indoor fan, outdoor fan. Compressor continues running. Machine jumps into cooling, condensor melts ice, either for 20 min timer or till temp rises. Then switches back.

[@beemikeme]

Thanks for spending the time to make all of your videos. I have watched many of them. You are one heck of an EXCELLENT teacher clearly explaining everything you are doing! I have a heat pump that is not cooling. The low side pressure is about 50 psi and the high side is about 150 psi. Both lines get neither warm nor cold. The indoor fan, outdoor fan and compressor are all working. Do you think the defrost board is causing the lack of cooling? Thank you, Mike

[@acservicetechchannel]

Hey Mike it seems that 50 psi would be too low and that you are low on refrigerant. You would check in subcooling if you have a txv metering device and check in superheat if you have a system with a piston as the metering device. Check out "acservicetech superheat playlist" and "acservicetech subcooling playlist" thanks

[@ramonvenegas8535]

this channel is the best thanks for you explain

[@acservicetechchannel]

Thanks Ramon!

[@foxmar2005]

❤thank you so much

[@soulme8186]

thank you for your video I have a question about the high pressure wire connected to the contact could you please explain that more

[@michaelcostello6991]

kzbin.info/www/bejne/jqLLYn6Epb98p7M

[@josephcaramelli1155]

thanks a million ,

[@maxxdanero]

Quality teaching!

[@munawarsoomro6207]

PS thanks for awesome videos. Enjoying your eBook as well.

[@padilla7019]

Very helpful video

[@acservicetechchannel]

Thanks Luis!

[@hvacguy9319]

Thanks man

[@acservicetechchannel]

You're welcome!

[@felipeballi7679]

great vid, took these instructions with me to a job and wow everything you pointed out i tried and it worked. also did as Bernie suggested and did not leak the hi and lo pressure switches, gotta have safeties. great job, great job

[@acservicetechchannel]

Yes keep the pressure switches in series with the 24v power going to the contactor thanks!

[@NeGBusa]

Are you getting power from the batteries from the thermostat to turn on the condenser

[@hvaclifeatx7012]

Those that same concept works a American standard board?? Good video 👍🏻

[@WayneKellen]

Great video. I've been trying to troubleshoot a system. Basically it heated great, but once switched to cool it short cycled. I thought the defrost board wasn't controlling something right. I connected the Y from thermostat to Low Pressure switch. From there I connected the reversing valve and contactor wires. Then common to contactor and reversing valve. I also moved the fan to the contactor. The contactor jumped crazy when I turned it on. I took the low pressure valve out of the loop and it ran without stopping. I checked pressures and got a constant 75 psig and 240 psig. Looks like the low pressure was doing its job. However, checking continuity on it, it switches at about 150 psig. Is that correct? I can't find a spec on that switch for a 410a system.

[@sixtowerhvac9133]

Will this work to use a heat pump as a straight cool unit

[@damionelliott2517]

This guy is a beast at HVAC!! I ran into a situation like this before and honestly I panicked 😱 but this video definitely is informative 👌🏼only wished you had run the unit so we could see it in operation.

[@rocker8692]

good explanation

[@acservicetechchannel]

Thanks Chad!

[@sal8575]

very thorough information! would it work the same if you attached one of the reversing valve wires with the yellow wires and the other reversing valve wire with the blue common wires?

[@acservicetechchannel]

Sure, that takes the board out of play, and then you are running cooling on most except ruud, rheem, weathermaker, thanks

[@toupsclassroomtoupsclassro9557]

nice video, but for a home owner just learning some ideas will need to watch a few times ty nice clean job............so for me, I would ck the voltage going into the transformer and coming out then i guess see if power is coming off the defrost board.............?? thanks again

[@neomacchio4692]

What is T1 and Y that you pulled and tested? I don’t have those in my Frigidaire unit ET4BE.

[@viper22304]

Awesome video, Thanks for sharing. Could anyone please explain to me why the RED thermostat wire was not used? Is it because the 24v is coming from the thermostat, energizing the COMMON wire from the thermostat.

[@atomicwalnut1581]

Thank you for sharing this info! I'm not getting a change when testing resistance with T1 and Y, meter stays at 1. I'm also not getting the low voltage to my contactor. I'm not sure if it's the board or a pressure switch that's bad. Contactor tests out fine, but it will not energize to make.

[@acservicetechchannel]

You should disconnect the compressor and fan from the contactor for safety. Then put one probe on common and one probe on the 24v hot coming off the board and follow the 24v through each pressure switch and/or temp sensors until it comes back to the board, thanks

[@atomicwalnut1581]

@@acservicetechchannel Thank you! I really appreciate the info. I'll run through that tomorrow.

[@neomacchio4692]

I have the same issue. I don’t see T1 or Y anywhere on the defrost control board. I have 24v at Y, but no 24v at the contactor. I have narrowed the missing 24v down to where it connects to the Hot1 and Hot2 which is the Hot Gas Bypass switch. HGBP. The schematic does not show how the 24v should reach that point. 🤔 I’m stumped!!

[@craigkachadorian3664]

Outstanding

[@acservicetechchannel]

Thanks Craig!

[@neomacchio4692]

I performed this and my AC works!! TY! However, my external unit FAN doesn’t ever turn off, even when I turn off “cool” on the thermostat. Did I wire the fan wrong?

[@danielogg5446]

thanks for all the great info. mine just runs and runs. the air is never cold in the summer and never warm in the winter. its a 10 yr old 5 ton heat pump. what should the temp be coming out of the register?

[@alchemyphilosophersstone2634]

Great video

[@acservicetechchannel]

thanks

[@aicilopon26]

Would it be good to connect your pressure switch in series with your contactor in case that the pressure drops it would stop the contactor?

[@stevehayton746]

Could you please explain about 6:39 minutes into video you took hot wire off of contactor, which you said went down to a pressure switch. You also said had to go thru pressure switch in order to have power come into fan relay. I am a bit confused here since I cant see diagram for unit. What pressure switch are you talking about and how does this effect power coming to relay?

[@MikeHilton-k3f]

That is for the 24v going into fan relay on control board. He bypassed that relay since it’s on the bad board and wired it straight to contactor

[@TheStab7]

So what do you check for onRudd ?

[@aaronclark1599]

If I'm replacing a transformer in a carrier package unit that is missing, and is missing the wiring diagram, where would I hook the low voltage wires? The red goes to the R on the board, but what about the common wire? Does it go to common on the Board, or to the contacts? Thanks.

[@robertmunguia250]

Good video!

[@acservicetechchannel]

Thanks Robert!

[@SIX673]

great video, keep up the good work

[@acservicetechchannel]

Thanks David!

[@danielallen8560]

David Barabin

[@jdr5501]

The condenser fan motor relay on the defrost board is normally closed. It only opens on a call for defrost; therefore, there is no need to remove wires for condenser motor in this case. The 24 volts to board has no role in keeping motor relay closed.

[@acservicetechchannel]

This is true but as a precaution if the board is bad, I would go ahead and just take the board out of play if it is intermittently working or bad and this is the first time at this job site. I would only be doing this for a short while until I get the board to be sure and while it is in ac mode. Thank you very much for your comment!

[@edmeizter8921]

jdr5501 Qq

[@gmac280]

I just had to replace an outdoor condensing fan and the defrost board had to be bypassed in order to run the unit in ac mode. I just jumped out the fan relay and tied the outdoor fan right into the contactor and it ran fine and now it just shut off according to the homeowner. It"s a Payne unit. I'm guessing I have to power the reversing valve as well as you just did in the video. If so why did it run fine at first.

[@acservicetechchannel]

The reversing valve would need 24v on it if it is a Payne for cooling, thanks!

[@musclemoney4479]

I love your videos. Im subscribed. I had one question. Do you have to bypass the defrost board for Air conditioning everytime on those models if the defrost board goes bad? Even if it were cooling season and the tstat was set for cooling. Im trying to understand,i almost got it. I just dont understand why they would route the defrost board in cooling mode. Any input would be appreciated , thanks, keep up the great work.

[@MaMa-qh4dy]

In order for cooling to work on a heat pump, a properly functioning defrost control board is required. If the board is bad and you want to know how to bypass the bad board so that you have cooling, just do as Craig showed in the video.

[@somunnavuie9167]

Thank you very help full What wire I should use if my thermostat worked with batteries and I don’t have blue or commen wire coming from thermostat ?

[@acservicetechchannel]

You would still have a c coming from the indoor unit even if from your indoor unit to your tstat you don't have a common, thanks

[@somunnavuie9167]

acservicetech thanks

[@felipeballi7679]

great vid. great job.

[@acservicetechchannel]

Thanks Felipe!

[@toddiamhvact7386]

yes you could use emergency heat. You could also use heat pump for heat. Just have one contactor for the compressor and add one for the OFM making two motor controllers. Wire DFT in series with the contractors. When the DFT senses a low coil temperature it will essentially initiate defrost by cutting out the OFM. Of course this would only be a temporary fix because you would only be initiating and terminating defrost by temperature only but you would still be able to use heat pump for heat. Without the defrost board you would not be able to initiate defrost by time.

[@acservicetechchannel]

Todd, your thinking in the right direction, how do I get the customer heat if there is no secondary heat. My concerns. The dft is normally open. The dft would be closing constantly since the temp on the coil would be lower than 32 any time it were 40 degrees or lower and would close because the coil is absorbing heat from the cold ambient air. Most DFTs close at 27-32 degrees. To do what you mentioned you would also need a general purpose relay. Of course, anything could be made but a timer would be needed so the unit is not running in defrost mode so much putting cold air in the house. Thank you very very much for the thoughts and ideas! I do agree, just move to emergency heat temporarily. Thanks

[@toddiamhvact7386]

acservicetech Most DFT switches I have come across are NC but I know some are NO but like you said it depends on the manufacturer and what your unit schematic says.

[@acservicetechchannel]

Thanks for your comments Todd!

[@aircooledtx]

Why not take rv to contactor, then only have Y -common to make up??

[@acservicetechchannel]

I didn't want to confuse those who are working on ruud rheem and weathermaker as they will not be powered in cooling mode but for the other manufacturers you are absolutely right! Thanks

[@matthewszikney9574]

Let's say I bought a new defrost board and I'm reversing the bypass. Does it matter which two orange wires coming from the reversing valve go to C and O on the deforst board?

[@davepedersen6984]

Doesn't look like this unit has an outdoor thermostat. Would an ODT have any effect on strictly cooling? Or would it change this bypass method?

[@acservicetechchannel]

The odt sensor would just affect it for heating mode, not cooling mode, thanks!

[@bernieclement3373]

Why leave the High pressure switch and LOC switch plugged into a dead defrost board. They should be in series with the yellow compressor 24v coil regardless how temporary this is.

[@acservicetechchannel]

Ha, I'm glad you caught that. I mean't to do that in the video and I see I did not. I will put a note in the video during that section. Thank's alot Bernie. It's been a long week. Teaching HVACR daytime, night time, as well as night service calls, and weekend installs! Thanks

[@edselectricwired]

electric furnace wired

[@jeffwilson6088]

How do you run the wires for the high / low pressure switch after bypassing the defrost board ? Any help will be greatly appreciated. Thanx

[@builder229]

They should be in series with y. So that when one of those switches open it kills the call for cooling on the contractor

[@mikeyangel1067]

What is the model of the HeatPump you are working on? Tnx

[@5822huron]

brilliant

[@acservicetechchannel]

Thanks!

[@BillyN31]

Do you need to power the reversing valve it the board failed in cooling?

[@geojor]

just great, thanks ...

[@acservicetechchannel]

Glad to help!

[@papoloco34]

can you please do a full PM video in a heat pump unid...Thanks

[@acservicetechchannel]

Thank you for letting me know what you would like to see in new videos!

[@drummerdem50]

Great idea,would also like to see that.

[@dckid571]

Can you help me understand im new to this trade but i have two questions... Is t1 common? And is t1 and y wired in series thats why you can check for resistance? Sorry if theyre dumb questions its just bugging me

[@acservicetechchannel]

Y goes through the safety sensors and then powers T1 on the board which initiated the timer. The sensors are just breaking the hot for safety and is not a common. With the power off you could check for resistance if the wires were disconnected off the board. The high pressure and high temp sensors wouldn't trip though unless the system was on and had a problem. Thanks

[@dckid571]

+acservicetech thank you so much! You truly are the best when it comes to explaining and your videos are helping me understand hvac faster than any of my previous trade school teachers. God bless and thank you again

[@acservicetechchannel]

Thats awesome to hear man! I just got done teaching my high school students and now my Adult night school students for the night. Figured I would check in on you all. May the Lord Bless you too!

[@ramongalaz6263]

I Have a York 5 ton package unit heat pump.Changed a bad circuit board.But know i get heat when thermostat is on cool and cool doesn't turn on.Maybe swapped wire or bad thermostat?Thank you.

[@cbharis]

Will this work for Payne units?

[@cbharis]

I went ahead and tried this on my Payne unit. I was able to successfully get the unit running but it was not cooling. So something must not have been correct. Ideas?

[@acservicetechchannel]

This was a carrier unit which is the same manufacturer as Payne and Bryant. It sounds like maybe you are not sending 24v to the reversing valve if it is running in heat mode, thanks

[@cbharis]

I went back out there and double checked all my wiring. Still no go on the cooling process. My next question would be, do you think it's the defrost control board since the unit was not running before I bypassed it and now it is at least "running" (coming on) after I bypassed it? If so I'll just run and pick up a defrost control board from my local distributor. Many Thanks for the help in advance! :)

[@acservicetechchannel]

When you say it isn't cooling, is it just the fan running or is the compressor running as well?

[@cbharis]

Well, found the issue today. There was a hole in my line inside the condenser, where the lines were touching (from the factory) and from all the vibration, it put a hole it in! :( Sad.... sa day! Had to get a man out to solder it up and add 5 pounds of freon! Ouch! But on the bright side, the house is cool again! :)

[@eman3208]

Hi service tech,Im trying to troubleshoot a Rheem and everything operates well in cool mode, but when i turn heat mode on the reversing valve energize but i dont get the 24 volts from yout and cc to energize the contactor and after a few minutes fan and heat strips come on and it keeps operating that way... any tips what should i be looking for? thanks in advance for your response.

[@mgoblueguy]

Do you have any videos about controlling my lp gas furnace blower only while using my outdoor wood boiler, while maintaining the ability to allow the gas furnace to operate normally in case of low water temperature? I want to be able to feel comfortable knowing my house won’t be cold if I go away for a weekend without having to adjust bunch of things.

[@acservicetechchannel]

I don't have any videos on that but when I have installed them in the past, I put an additional thermostat in for the wood boiler heat circulator relay and another relay in the boiler to turn the circulator on or in a furnace to turn the blower on. Then the homeowner would simply put the boiler thermostat 10 or 15 degrees lower than the wood boiler thermostat, thanks

[@mgoblueguy]

AC Service Tech LLC , I have lp gas forced air though. If I had an indoor boiler this problem would be easy for me. What I can’t get figured out is this, with the two stat setup as provided with the Central Boiler manual, it would allow the gas to back up my OWB but my furnace blower would run constantly so long as the boiler stat was calling for heat, which it would be. I could pull 120v from the fused side of the furnace circuit for a line voltage stat with the switched side going to a low temp cutoff in my OWB supply and then to a parallel tap on the board for the blower. I’m confident this would achieve the end result I want, however, I really don’t want a second stat, and I haven’t found an economical option for that low temp cutoff. I would be happier with a 2-stage t-stat IF it would work for me. I’m just not able to verify whether that would work. Other than the defrost portion of a 2-stage stat, it seems that in heat pump stage all that happens is the blower is on or off when 1st stage is calling for heat. If it doesn’t keep up, the 2nd stage kicks in allowing the furnace to operate as it normally would, but I’m not confident that the fan wouldn’t still run constantly as with the two 24v stat setup. In a nutshell, I want a worry free automatic system that takes no special measures on my part and something my wife can not have to bother with.

[@mgoblueguy]

Can you confirm whether the 2-stage thermostat would work for me or not?

[@acservicetechchannel]

I wired about ten outdoor boilers to do what you are looking to do and always used a separate 24v transformer along with a second thermostat. You can't have two separate 24v transformers in a thermostat that are both for heat, thanks

[@mgoblueguy]

AC Service Tech LLC , Thanks for the confirmation. Was there any need for a low temperature cutout to prevent the blower from running or not?

[@papoloco34]

can you please do a video in condensing unid and air handler installation and a video in how to read schematic diagrams...thank you

[@acservicetechchannel]

I do plan on making a reading of diagrams video, thanks! Check out the brazing with nitrogen playlist on the channel site. There I have a three part video of coil and outdoor unit install. Thanks

[@papoloco34]

I did already I've been watching your videos for the past two days all day long...and I still have like 100 more to watch...thank you and keep posting good videos.

[@acservicetechchannel]

Thanks Pedro and every one of your comments are appreciated. They also help the videos be found by others because of comment ranking on youtube so if you do enjoy them please keep up the comments even if they are a few words or thoughts on the subject. I also like to hear what you all would like to see coming up in the future as well! Thank you!

[@julito1959]

Pedro Rodriguez porque se congela el condensador en heat pump

[@yewannahtay8949]

Pls explain with single line dwg so that we can understand easily.

[@wannis100]

HiFirst of all, I want to say you work is greatly appreciated. I have been listening to your videos all the time and I have learned a lot. I want to ask you a question on Mitsubishi City Multi VRF system. I was at one site location where company had install multiple City Multi VRF system with multiple BC controllers. At one particular room with three ceiling cassettes one thermostat during hot day when thermostat demand cooling, warm air blowing from cassettes. Apparently the company who installed it was not able to troubleshoot and some other technicians where not able to troubleshoot also. Do you have any idea what is happening? Or what would be the cause of this. Thank you.

[@actarusfleed6607]

The VRF is a garbage system. Every fitting and length of copper tubing has to be engineered right on the nose plus the fact that there are no isolating refrigeration valves make it worse as God forbid should you have a leak, the whole system charge will have to be recovered. You cannot isolate any section. What a shame. Sure there's no need for ductwork however, I prefer the KISS Method. Keep It Simple and Stupid.

[@VeryPersian]

So wouldn't this setup work for heat as well? Just no defrost. Right?

[@acservicetechchannel]

Yes it would work depending on how you power the reversing valve but once it is 40 degrees outside, the coil starts to freeze because the temp on the coil is lower than freezing. I would not damage the outdoor unit accidentally because I won't be there to monitor this. Thanks for the question!

[@VeryPersian]

Not critiquing, but to avoid possible condenser damage wouldn't make sense to not wire the reversing valve. So if heat were selected on the thermostat cool would run thus avoiding possible condenser damage. So the reversing valve could be wired in line with the yellow from the thermostat with both wires in series to the contactor.

[@acservicetechchannel]

Correct, this video was only a representation of what to do in the summer to get the homeowner cooling but the video also covers ruud and rheem or other manufacturers so no one gets confused because the reversing valve signal is still coming from the thermostat correctly. I just didn't want anyone to get confused and wire it wrong. You certainly can wire it exactly the way you are saying if the brand is one that only powers the reversing valve in cooling. This video is only if you were coming back with the board soon anyway. Thanks for the question billy bob!

[@arrealhandymanservice4459]

So on this unit it will go into heating also ?

[@jeffwilson6088]

What if your not getting omws from T1 to common ?

[@bass3man2u34]

Can a heat pump system have both type of valve on one system. piston at condenser and TXV at blower? Thanks!

[@acservicetechchannel]

Yes that is correct, thanks and I just sent you a link to a video to discuss that

[@Forextrader19]

Just graduated HVAC trade school and have a buddy that's having an issue with his outdoor heat pump unit. Says he hears his outdoor unit run randomly in cool (lives in las vegas about 70 degree weather currently). He noticed it because his unit is right next to his bedroom. Thermostat is set to off the times that this has happened and the said he didn't feel any air coming out of his Vents. Told him to check for any schedules on the thermostat and there was none aside from it already not calling for it because the tstat is off. What are some possible things that can cause this. When I went I didn't see anything out of the ordinary and it happens randomly.

[@jonathansorise8797]

Sounds like he may have t stat wire (Y and R) that is touching. Likely at the outside unit. Perhaps wind hits the wire just enough and sways it enough to power the outside unit. That is if it's super random and has no air flow inside when that happens.

[@Forextrader19]

@@jonathansorise8797 I don't think it's winds causing this issue. But I checked all connections and found no uninsulated wires or wire terminals close to others to cause this issue

[@aaronshoyt]

Question. I have power going into my board, but no led lights are on and no power coming out to my contacts. Thats a bad board right? But why is there no led lights showing i have power when i do? Thanks

[@terrym4616]

Looking at installing a heat pump and air handler with electric strip heating for back up. I am replacing a 15KW (no heat pump) strip heater air handler. Can I downsize to a 10KW heating strip as when needed it is only adding to the heat provided by the heat pump?

[@acservicetechchannel]

The heat pump won't be supplying heat at lower temps and since you already have the correct electrical supply, you may want to stay with the 15kw but basically a heat loss calculation on the building would determine your heating needs during winter, thanks

[@aicilopon26]

And my defrost board is bad but I can find the oem one, could I use a board from another manufacturer that has the same functionality just different locations for the components?

[@rogercerasoli7875]

I'm getting 24 volts from O to C, but nothing from T2 to C. T2 runs directly to the contacter switch. There is no resistance in the T2 wire. Can I then assume the control board is bad? Thanks!

[@sixtower]

can you bypass pressure switches to check by jumping T1 and Y

[@phototec]

I have a Lennox HP that has burned up 3 reversing valve coils in the last 3 months in cooling mode, the unit works and cools well until the coils short out and cause the 24v circuit to blow a fuse. Any idea of what the cause could be? Any chance the defrost board is bad and would that cause the r-valve coil to short out? Thanks for any guidance.

[@acservicetechchannel]

Usually the power for the reversing valve is not stopped at the defrost board but flows through it. Normally when coils burn up it is because they are either powered on all the time or are not pulling on a load such as they may not be the direct replacement from the manufacturer that would fit well on the reversing valve cylinder. Thanks

[@Josh-px6xb]

I went to troubleshoot a friends heat pump package unit and they had switched back and forth to a smart Tstat and I guess had heating problems in the winter and they put it back to the old tstat. Well now it didn’t want to energize to cooling and I wasn’t getting 24v to the reversing valve. (The tstat wasn’t sending the signal I guess) so just to get the cooling temporarily, I bypassed and wire nutted the orange wire to the Red wire and it worked fine.. I need to figure out what the issue could be.. any advice where to start?

[@acservicetechchannel]

Did they not connect the tstat O wire, sounds like they need to connect to O and not B because of having to power the reversing valve in cooling mode. Check for dip switches in the old tstat and any programs that will tell the tstat what it is connected to for instance if the tstat thinks it is connected to a furnace and ac. Not sure what tstat this old one is so there are some things to look for, thanks Josh!

[@Josh-px6xb]

Thanks for the response. I believe the old tstat just has a B terminal and it is only a 5 wire tstat wire. And Yeah I was thinking maybe they didn’t program the Tstat to a heat pump but that tstat is older and I doubt they have any instruction manuals to re program it . im suppose to go back to continue troubleshooting further and I’ll look more into the tstat itself but the system was 4lbs low on charge so I’m suppose to go search for a leak also. Some oil residue near the discharge line after the compressor so hopefully I’ll be able to find it with some bubbles and not have to purchase a leak detector

[@Josh-px6xb]

AC Service Tech LLC So they don’t have that extra wire for common. Will that affect any troubleshooting with a voltmeter?

[@catdaddy7582]

After checking all inputs and outputs, and bypassing the board, I am real sure the board is bad at my ex's house. all 24 volt inputs are good, switch circuit has continuity, temp sensor at 5kohms. Unit has been bypassed and operating normally for several hours. Here's the rub- it's a Diamond Air model d1336hcb I installed myself 7 years ago. (I believe the electrical storm got it- we had one the night it quit- got the thermostat, too.) The board at Budget HVAC is 225- that's godawful high for a defrost board. ONLY source I've found to date. Can I not use a cheap Goodman board or something else with the basic connections? and does it HAVE to be from a unit that reverses on heat (this one does), if I wire it to operate correctly? Got any suggestions? I have another quadplex besides this house with 6 units- I need your book! \

[@corywade4702]

Would a trane defrost board cause the Compressor not to kick on while the fans running I keep hearing a clicking already tested the capacitor ~

[@acservicetechchannel]

Usually the defrost board is needed in order for the compressor and fan to both turn on by powering the contactor. Then the defrost board relay just controls if the fan is on, thanks

[@attissotogbo6981]

Can this troubleshoot be done on any defrost board ?

[@acservicetechchannel]

You would need to look for a defrost sensor if it has one and speed up terminals if it has them, then yes you could s they are made for testing. Some older ones are just timers for defrost though. Thanks