Crucial Knowledge To Heat Pump Troubleshooting

[@RalphMercuroMusic]

Hey Mike, There's one small detail missing from this video. DFT = Defrost Thermostat. It's a SPST NO switch that closes on a drop in temperature. It's located on the outdoor coil to sense the temperature of the outdoor coil during heating mode. Typical setting is 30-35ºF with a differential of 20-30ºF. The actual rating depends on manufacturer. The Defrost control will only accumulate compressor run time while the DFT is closed. If the DFT opens in between cycles due to outdoor temperature, the defrost control will start accumulating compressor run time (starting at zero) during the next cycle after the DFT closes. The defrost control will add up the cycles only if the DFT remains closed in between cycles. If the DFT remains closed long enough to accumulate the selected minutes on the defrost control (Typically 90 minutes in North America) a defrost cycle will be in initiated. One of two things will terminate defrost. The DFT opens due to the coil warming up, or a maximum defrost time is reached. This is a common Time & Temperature Defrost control...

[@JerseyMikeHVAC]

Thanks for the added detail. I'll pin this to the top of comments so people can see it. 👍

[@samyz1660]

I’m in the south, hot weather, rarely when I get a heat pump call. Trying to learn. I lost it a bit but will watch it again, and again until it clicks. Thanks Mike.

[@JerseyMikeHVAC]

No problem. I know it's a lot to take in, but it's mostly all there.

[@cataclismdeathsassassin1698]

This winder hitting the south is definitely causing a bunch of calls. I'm surprised on the number of Units that simply never had their heating coils connected and their reversing lines ignored.

[@Zepsswansong]

Well done! 40+ year tech here, awesome video for young people in the trade. thanks for such a great explanation and fantastic graphics.

[@JerseyMikeHVAC]

Thanks!

[@miguelrojas3394]

Oh my GOD ,this is one of the best explanation and example of the sequence operation for heat pump I ever watched thanks Mike.

[@JerseyMikeHVAC]

Awesome! Thank you.

[@binfeng8905]

This is a perfect explanation. It explains the principle in the simplest words.

[@mythoughtsgenx]

I am a hvac contractor I've been doing hvac almost 30 years! I truthfully don't know how and or why I watched several of your videos. With that being said I think your awesome truthfully should be a teacher, you break everything down! I actually gave your channel to one of my tech, he is having a hard time. I walk up fix but not a teacher good work brother!

[@SeamusDaly-oc3yw]

Thank you Mike, just fantastic explanation

[@JerseyMikeHVAC]

Very welcome

[@thejflores1219]

You got the best videos on YT for hvac wiring schematics. THANK YOU

[@JerseyMikeHVAC]

Glad to help

[@joeseda8102]

Hi Mike, You have proven that a picture says more than 1,000 words! I have learned much by reading and listening to others, but actually having travelled through the electrical system and being able to visually see the flow of current through the whole system has truly given me a lot more and clearer knowledge of an HVAC system! I congratulate you for such a wonderfully put together VISUAL experience. Took the time to check my home system and was able to verify what was expected to happen 100% of the time. I had never felt so comfortable checking my system. Thank you GREATLY! Graphics and explanations are AWESOME!!!

[@JerseyMikeHVAC]

Thank you, brother. Love hearing back how my videos are helping out.

Thank you Sir, for this awesome video. You have cleared up quite a few "cob webs" for me. I was able to find the answers for myself after your explaining. NOW, I really understands completely the electricals on heat pumps systems. I literally visualize testing this circuit, with an 'ampbrobe", and correctly got EXPECTED results. Now I am really confident, to tackle these monsters now. WOW!!! Thanks again so much, God bless you Sir.

[@JerseyMikeHVAC]

Excellent!

[@michaelbroadbent4703]

this vedio is remarkable, love your visual. Thanks for the info and making easy to understand. awesome

[@JerseyMikeHVAC]

You're very welcome!

[@PaulRiordan-bt3nu]

I teach HVAC in a high school in the Boston area. Stumbled upon your videos and the students really enjoy them. Some of the videos we find are too vulgar or too boring. We have not seen you on the videos so everyone tries to describe what you look like. The common theme is that no matter what you look like they all say you are an HVAC BOSS!!! and this is from your Boston area rivals!

[@PaulRiordan-bt3nu]

When I was talking about vulgar or boring I was talking about other videos I find on the internet, not yours.

[@JerseyMikeHVAC]

Thank you! You know, I used to live up there for many years. Some family still does. North Shore. You guys are alright in my book.

[@tjlovesrachel]

@@PaulRiordan-bt3nuif vulgarity bothers your students they aren’t built for the trades… I’m sorry

[@brianmcdermott2430]

Great info. and graphics. Thank you , Mike.

[@IRFANCINEL-gj8dy]

First time in my life subscribed to u tube channel , this is best explanation out there . I have no doubt in my mind you will grow big . Explaning how power flows from point A to point B with schematics really clicks . Thank you for all this good work .

[@JerseyMikeHVAC]

Thank you. Honored to have you!

[@jasonseifried7192]

This is amazing video. I been in installation for 20 years and been doing service work for a few months now. And installation has helped me to be a better service technician. But still installing and servicing are a different experience for sure. But this video has helped me tremendously. Thank you so much

[@Goliad_Respector]

Best HVAC channel/instructor on KZbin hands down, the current on the diagrams is so helpful I can’t thank you enough. I wish more students would take advantage of your resources, extremely helpful.

[@JerseyMikeHVAC]

Excellent. Thank you!

[@louisviciedo]

great and very detailed video. thank you

[@BeersHVAC]

Love this video! Makes things very clear! Subscribed!

[@JerseyMikeHVAC]

Awesome, thank you!

[@studyallthetimeallthetime8473]

This is my new hvac bible for the next 2 months, amazing explanation thank you thank you!!!

[@youellplumbingadmin549]

Great video. This, combined with being at the actual ODU and physically following each wire from the DCB to each component makes it all so simple and clear. I’ve shared this with my techs, great visual guide and clear explanations.

[@JerseyMikeHVAC]

Thank you

[@8urrows]

Mannnnnnnnn you KILLED IT with this video. Dude if there's ever a contest to come run with you for a week or two please let me know as I'd love to shadow you for a week.

[@elgkas9928]

Another phenomenal video. The animation is great. I know that I learn better when I see a process.

[@JerseyMikeHVAC]

Thanks. Glad it's helping you understand it better.

[@jeanluc397]

this is a great video for me just started Hvac training 2 months ago so I'm a noob. gonna have to re-watch this about 20x though but no problem with KZbin. thanks

[@JerseyMikeHVAC]

Almost nobody gets it all the very first time. I certainly didn't. That's the beauty of replay!

[@keovongvilaykeo4799]

Great video thanks you 😊

[@gaberuiz3913]

Great video!! I'm only a third of the way into it and already feel like I've learned something.

[@JerseyMikeHVAC]

Great to hear!

[@tryscience]

Exceptional quality, is no accident. Thank you for your hard work

[@broncheemims8493]

Like the animation. Now I can really explain it now to my students

[@EdwardeliyahHamnerBoMF]

I truly love this animated video and it has helped me immensely.

[@JerseyMikeHVAC]

Glad it helped.

[@spok209]

these neon colors/effects really make the information stick. holy shit. Thanks

[@cleansebob1]

Best explanation I've ever seen!

[@Techstar52]

Such a great explanation, keep them coming! Grettings from Tx

[@davidstahl8917]

I just learnt more from this 1 vidoe then I did in 2 years of hvac school training. . . Awesome stuff Mike please make more videos explaining this stuff

[@jonathandavidwest]

Great stuff! It makes it so much easier to understand.

[@JerseyMikeHVAC]

Glad to hear it!

[@wim0104]

this PCB schematic stuff is awesome: augmented techno-vision !

[@JerseyMikeHVAC]

Making this video even helped me figure a thing or two out. ha.

[@mikemalone6103]

absolutely amazing how much effort you put into this video. visual is so much better. Great Idea......Now if you could make one for economizers next.......

[@jenko701]

Nice job , well explained.

[@JerseyMikeHVAC]

Thanks!

[@brianmcdermott2430]

Great info. and graphics. Thanks Mike.

[@vvsmixing]

Thank you so much for this detailed info i understand my system so much better

[@jacobreinen5392]

Absolutely phenomenal!! Thank you! Best schematic video I have seen EVER!!

[@jsnxng7578]

Wow, Very well explained & I took a lot from your video. Thank you!

[@pierceglynn3277]

Great video. Please make more like this.

[@JerseyMikeHVAC]

Thank you. I have a playlist with several videos like this: kzbin.info/aero/PLzqK-0xeBEzXzIz9eZAf9xTU8mnhbqXHz

[@WilliamNicholsLC]

This is the best video on the net

[@Leon55693]

hi, wanted to say that i've watched alot of your videos, very helpful & thanks alot for putting them out there. Some of them i had to watch a couple times to digest it. You explain things very well, not rushed or meandering around, good diagrams that are color coded to show the electrical flow. Ps - glad you don't use foul language and keep things decent!

[@hsuan-jenhankwang2448]

Thank you for your lesson ❤I am lov’in it!

[@antonioandrade3005]

Exelent class you are the best thank you so much great teacher 💯💯👍🏼👍🏼👏🏼👏🏼👏🏼👏🏼

[@BaljinderSingh-pn1mm]

Thank you sir 🙏 I am new in canada 🇨🇦. And sir watching your every vedeo . Thank you for explaining with schematic diagram ❤ awesome

[@TonyHoanz-vc2pq]

Thank you so much for sharing. Tony from Houston

[@JerseyMikeHVAC]

Any time!

[@alimahdavi01]

Perfect video and explanation. Thanks for sharing!

[@JerseyMikeHVAC]

No problem!

[@stevencossaboon3237]

Great job and video Mike. Thank you.

[@JerseyMikeHVAC]

You're welcome.

[@fernandoaguayo9304]

Mike you are best thank you for this type of videos!!!😊

[@JerseyMikeHVAC]

You're welcome!

[@deanmartin1966]

Great animation. Thanks for sharing

[@JerseyMikeHVAC]

You're welcome.

[@MDerrico710]

Great video! Thanks for sharing

[@ronkirkham3410]

I agree , great video overall. I have some basic questions if your available

[@sermore77]

Thanks great videos & explaining.

[@JerseyMikeHVAC]

Glad you enjoyed it!

[@TotalAirCareServices]

Excellent video MIKE!! Thanks for sharing !!

[@GotchaplumberGotchahvac]

Good explanation!

[@mariusm3595]

Mike I love your videos.....

[@JerseyMikeHVAC]

Thanks!

[@jeremyjedynak]

Great video, and explanation!

[@JerseyMikeHVAC]

Thank you!

[@Mondfriday]

Best explanation ever!!!!

[@tmyonthat]

Downloaded this 🫡

[@oilandfireguy1739]

Great video!

[@BaljinderSingh-pn1mm]

I subscribed your channel and shared your vedeo

[@JerseyMikeHVAC]

Thank you!

[@Bill_CBR]

This is great.

[@jeanlawson9133]

This is awesome...Is there a place I can find schematic on specific model...old Heil in particular.

[@travishodges5179]

So what would blow the low voltage fuse in heat mode but not in cool assuming no bad wires?

[@rioraton]

Hi, homeowner here. Just installed a venstar T8900 color touch Therostat for my 2010 older goodman heat pump and I have an old 1990 carrier air handler in the attic . This particular thermostat has 3 dip switch on it and I set them according to the instructions..I think :). I then hooked up the wires according to the instructions .. Red wire to power terminal, Green wire to fan Terminal, Yellow wire to cooling/compressor terminal, Blue wire to Common terminal, and white wire to O/B. The POS does not work right??? At first all I got was fan cuz I did not set the dip switches... they were all factory default gas/electric. After I did that I got cooling however after reaching desired temp the heat pump energized the heating and continued to run??? To stop this I put the white wire on to the Y terminal along with the yellow wire so at least I would get cooling? What the heck am I doing wrong?? According to the instructions I did it right... I took an old honeywell RTH 7600 off which was working great however, it was battery operated....if that means any thing but where I really screwed up was not taking a picture of where the wires went on this unit. Anyway, any idea why my new thermostat is acting the way it is? PS I have NO orange wire to the thermostat?

[@DrSolo-qb1ze]

Hello Mike. I was working in the field and ran across a thermostat that the voltage on the R and Y was 16 volts, it also showed 16 volts in the air handler and 16 volts in the condenser. Testing the Red with green, and Red with white both registered 27 volts. What could be causing the voltage drop? The contactor does not show voltage on the coils, but when testing the coil for ohm it shows 12.8 ohm and it also has continuity. What could be the problem? Thanks for your input.

[@channelname8623]

5:45 i didnt realize 120/240 ran through the fan relay on the defrost board. I thought it was control / low voltage that powered the relay, similar to a contactor.

[@JerseyMikeHVAC]

Low voltage does control that relay.

[@butlerstouchHVAC]

great vid

[@JerseyMikeHVAC]

Thanks!

[@thomaslindsey7685]

Obviously you are very familiar with the systems . I hope to get there someday. Thank you.

[@harrisonbyrd1317]

My Lennox heat pump has 24v at the O terminal on the defrost control board and the air handler control board during heating cycle and cooling cycle, this means the rev valve is closed all the time and the system runs like cooling cycle. when O is disconnected at the outdoor unit the valve opens and the system actually heats. Why would O have constant power? I don’t think it’s a defrost cycle causing it because condenser fan runs with O wire connected at defrost board. Could it be a wire is pinched somewhere and is being energized with R or Y?

[@jamesortolano3983]

Check if W from out door unit is hooked up to indoor unit on to ( W2 W3 TERMINAL IN AIR HANDLER) There is a jumper between both . W1 terminal in air HANDLER is for E-Heat initialized by t-stat inside house ,w2 from out door unit is powered when out door unit goes into de frost nd tells board to turn on e-heat at this time . When it's cycle is over check timer outside in unit ( 30 minutes where I put it ) it goes back to normal HP mode where hot refrigerant travels though indoor coil to heat home which takes place from W1 at t-stat giving the first call to refrigerant, unpon second call ( at set pin time slot like I put to 30 minutes) then it goes to e-heat Hope I didn't confuse you . Lennox is a dealer item only complaint installers and Lennox dealer s should be wiring your unit . Any other HVAC guy may not understand the W1 W2 W3 scenario. If your equipment is 5 years young or less I expect it's a wiring issue, not units . That is of course if indoor & outdoor unit are both Lennox. Hope you find this helpful

[@rafaelandreano]

Can you make a video with a due fuel system. Oil furnace/heat pump with a 2 zone system Honeywell please 🙏

[@10speed4]

When defrost mode kicks in, the reversing valve switches back to AC mode, the heating elements activate - what keeps the blower fan from blowing cold air through the heating elements?

[@jamesortolano3983]

Lol😂 you figured it out , NOTHING keeps it from blowing .Other than removing power to indoor fan ( which I believe you are talking about) as it's in heating mode we need fan to blow through heating element (s) depending on how many ,how big your system is . But at the same time we need the superheated refrigerant to melt the ice or if any on the condenser outside as it's only acting as an evaporator coil for defrost . So we can't discontinue refrigerant from traveling throughout indoor coil ( evaporator) at the time in this MODE 😢. AS Mike did point out the condenser fan outside should be off at this time to allow the super heated refrigerant to flow through condenser coils at a higher temperature than outside ambient air to melt any ,if any coil ice . I myself when setting up HP ( HEATPUMPS) Always set defrost to 30/60 minute cycles as I live in NJ myself .As does Mike I believe . Why a short cycle ? Well to allow the refrigerant to go back to super heatered in door coil as fast as possible nd not to rely on electric heat . I mean that is why you bought a HP so you can use the refrigerant cycle as much as possible nd only utilize e-heat at the most difficult ( temperature drop dayz) . So yes you did figure out the secret we do not tell home owner s about . But I hoped I have explained why it's nessesary to have it blow over coil in electric heat mode ,while coil is in a/c mode . It's also helping to superheat refrigerant to out door coil as to make it get back to heat ( HP mode ) faster to eliminate a/c mode Also why I put to 30 minute cycle s

[@harrisonbyrd1317]

I am having an issue where I have 24v at the O terminal at the defrost control board and air handler control board during a heat cycle on my Lennox, this closes the reversing valve and runs the heat pump in cooling mode full time. (Cooling mode still functions as the O signal is sent then too). When I disconnect the O wire at the defrost control board the valve opens and the heat cycle runs properly, I think I have a wire pinched that is energizing O wire all the time, could it be that simple? I don’t think it’s a defrost cycle being triggered because the condenser fan runs when O wire is still connected at defrost control board.

[@JerseyMikeHVAC]

Did you check if the thermostat itself is sending out the signal on O in both cooling and heating mode?

[@Found4655]

In heat mode. Can a compressor be dead and the fan still run? A tech told me the compressor is bad even though the Fan blades on the outdoor unit are still turning. Unit runs constantly 24/7 even though thermostat panel says set point has been reached at 70 degrees heat. No intermittent cycling off at all. I believe the system is running the heat strips and not cutting off at set point of 70. Thermostat has been changed out. I am at a loss.

[@JerseyMikeHVAC]

Yes, it is typical for the condenser fan to continue running even if the compressor is bad, but my response is not a second opinion confirming a faulty compressor. A bad capacitor can cause the same result even with a good compressor. The unit could be making an attempt to run a defrost cycle even if the thermostat has satisfied, but the outdoor fan motor should not run during defrost attempts. If it is always running and never shutting off, this indicates to me there is different issue a bad compressor by itself doesn't fully explain. Could be the defrost control board is the problem, for example. A bad board could cause all of these same symptoms even with a good compressor or could even be the reason the compressor is now faulty. I obviously cannot say for sure without a proper diagnosis. I would suggest getting a second opinion.

[@Found4655]

@ Thank you. It seems companies now only want to replace and not properly diagnose. It could be acid cause the unit is only 5 yrs old. And the inside unit coils have been replaced recently. Its a 5-6 year old Trane and been acting up for 2 yrs. May have been a bad install cause its been serviced twice a yr.

[@JerseyMikeHVAC]

@Found4655 That's certainly a possibility.

[@kevinlee3334]

Hey Mike thanks for the amazing video. I have a few questions if you don't mind taking the time to clarify a few things. 1. When the unit is in defrost mode, how does the low voltage defrost relay get pulled in to pass 24v to the reversing valve? In the video you just state that the relay gets energized but I'm uncertain how that happens. Is there something internally that's happening? 2. Likewise how does the high voltage defrost relay open during the defrost cycle? 3. Finally just a general question but I'll reference the video as an example. When the Y terminal is pulled in and it sends 24v through the control board and through the pressure switches, how do you know that the 24v then goes to the M terminal? If I were to look at this on my own for the first time, I would have no idea that the 24v will come back to the PS terminal and internally to the M terminal. Obviously you've been doing this for many many years so you know by experience but how would a novice like me be able to figure that out?

[@JerseyMikeHVAC]

Both defrost relays are activated by the 24v signal passed on by the defrost timer taken from the R power. As for the M terminal, that one I just had to figure out by talking to other technicians or checking schematics of similar systems that laid it out a little better. It didn't come easy.

[@tmyonthat]

Uh oh, my customers are gonna stop calling me after seeing this!

[@mrcoz1764]

Can you tell me why my fan runs as soon as i turn on my heat pump ??? Thermostat pulled off,,,fuse blown,,,, New fan board,,New Sequencer,, yat as soon as put in the Breaker,,,it starts running

[@grashoprsmith]

Amazing video considering he's communicating through time from a helicopter in Vietnam.

[@JerseyMikeHVAC]

...as a double agent...

[@filemontorres7635]

Do you have a website, do you offer an online course?

[@JerseyMikeHVAC]

Not yet but I'm trying to find time to work on all of that. Eventually.

[@JohnSmith-lq8ib]

I need help. I have a Rheem system 3.5 ton, 20kW heat strip. From the control board I have the following wires going out of the cabinet Yellow connected on the thermostat at Y1. White and blue to W2. White and black to W1. G to Green. C to brown and R to red. On the defrost board outside I have the following letter and cable wires Y with yellow wire, B with blue wire, D with purple wire, Red with red wire and C with brown wire. I don't have "O" in the blower or on the defrost board nor orange wire. The thermostat am using is Nest Thermostat. What am I missing? The AC and or the Heat has never worked. No need to rush since the house is vacant but, I will be moving in this summer. What can I do? I see the RV and C on the defrost board connected but, I haven't follow the wires. I also see 2 flashing red lights for about 2 minutes after that, they start alternating on and off for another minute or 2 and start flashing at the same time. Flashing at the same time is normal. Alternative is High and Low pressure lock out. At this moment I just need help with the "O" wire and or terminal that I don't see anywhere. CORRECTION. I got the heat strips to work

[@JerseyMikeHVAC]

On Rheem systems the reversing valve is energized in heating mode off of the B terminal. So there is no O terminal used here. That blue wire on the B terminal on the defrost control board needs to be powered by the B terminal on the thermostat and this connection from B to B happens inside the air handler at the control board. That blue wire in B at the defrost board should go to B in the control board which goes to B on the thermostat.

[@JerseyMikeHVAC]

Also, the purple wire off of D on the defrost board should go to W1 W2 at the air handler. That is your heat strip activation during defrost cycles. Here's a wiring diagram you should be working off of: www.doityourself.com/forum/attachments/thermostatic-controls/54963d1440259155-connecting-thermostat-rheem-heat-pump-system-rheem-thermostat-wiring-diagram.jpg

[@JohnSmith-lq8ib]

I have no letter “B” on the control board. All I have is: Y1 = yellow wire W1 = white and black wire W2 = white and blue wire G = green wire C = brown wire R = red wire But no letter “B” or letter “O”

[@GotchaplumberGotchahvac]

Mike, saw a nest thermostat, yet Rh & Rc were not jumpered. Is this done in background on these thermoststs?

[@JerseyMikeHVAC]

Yes, all Nest thermostats have internal jumpers and will alter function based on what wires the thermostat detects.

[@SC-lm4yw]

excellent, love the animation ***strongly dislike Google Nest***

[@JerseyMikeHVAC]

Me too

[@PhillipFrischman-vo8gm]

I can't see the hole picture

[@alfredosanchez8592]

I have a similar problem with the letter O. I have a Rheem 3.5 Ton AC. I have the following wires coming out of the defrost board. Brown = Common (letter C), Red = Power (leter R), Purple = ?? (Letter D)Blue = ??(Letter B) and Yellow = Y (letter Y) which is for they is for the AC. My problem is the Blue and the Purple. Blue is connected to letter B on the board and Purple to D. The thermostat am using is a Nest Thermostat and it has letter B. It also has W1 and W2 adn from the board in the attic, I have w1 = white and blue wire and W2 white and brown wire. Assuming I connect Blue to B on the thermostat, what do I do with purple? I read some answer below and it suggest to connect Purple to W1 and W2. Once I do that, it will be like placing a jumper from W1 to W2, correct? If am wrong can you please correct me on all and everything.

[@JerseyMikeHVAC]

For clarity, when I said W1/W2, I didn’t necessarily mean place it on both and jumper them. I just mean it should go to one of those terminals depending on how it’s wired based on the configuration of the equipment available, which is information I don’t fully have. There may be 2 stages of backup heat in which case W1 and W2 are wired to each activate one of two heat strips or a 2 different stages of a gas valve in a furnace. All that purple wire off of D does is allow the condensing unit to activate whatever that backup source of heat is. So it will land on the same terminal that calls in the secondary source of heat such as heat strips, which is usually W1. In some cases W2 might do exactly the same thing, just at a different time and it might not make a difference if you place the purple on w1 or w2 or both. Normally it will just land on W1.

[@alfredosanchez8592]

@@JerseyMikeHVAC Never worked on an AC of any kind. Your video was a great help, not only that, you answer my questions prompt and to the point. Today I got my ac running, well my heat. Since I have a Nest Thermostat and the temperature outside was below 55 it won't let me turn on the AC but, I guess that will be another question for the summer. Thank you

[@xsivemotorsports]

Asking for a friend..... My friend had a company come inspect they found no 24V on the yellow at the outside unit. it was a open float switch because of a clogged drip line. they fixed that and everything was fine for 3 days...... fast forward 3 days and the AC is blowing heat. the Copper lines in and out of the outside unit was way too hot to touch, my friend pulled the cover off the unit to check for 24v on all wires and if the contactor works. what my friend found was the O wire spade had fallen off the defrost board. My friend plugged it back in, BUT AC is only matches outside/Ambient air. The guys that "Fixed" it say the outside is "dead" (6 year old Goodman) would running the system in "A/C" with the "O" off the defrost board "kill" the outdoor unit? It's my opinion they yanked the O wire loose on the defrost board checking for 24V. ?????

[@JerseyMikeHVAC]

The O wire just controls the reversing valve to put it in heating or cooling mode. It was blowing hot air because the RV wasn't getting the signal during cooling mode. Basically, having the O wire disconnected is just heating mode and shouldn't "kill" the outdoor unit. My question is was the O wire touching anything when disconnected? Could have created a short when powered up in cooling mode. Does heating mode still work normally or is it the same ambient result? If heat works, try to jumper Y and O at the defrost board in cooling mode. If ac works then, problem could be a burnt out switch on the thermostat from the short. If not, could have damaged the defrost board or possibly the reversing valve is stuck. At 6 years that could be a warranty repair.

[@frankiefrank4853]

Mike, do you have an Instagram? I have a low voltage company and the alarm systems we install are now probinding low-level automation features suck as lighting and thermostat controls. Your provided understanding of HVAC has now gone unappreciated. Thank you from Arizona.

[@jrsmyth9761]

How do you use one of the WORST thermostats ever made, especially for a heat pump?

[@JerseyMikeHVAC]

Because 8000 people will ask me how to hook up a Nest with it, so I just did it with a Nest.

[@frankroper3274]

This video could take you a long way to finding the problem. Careful about touching things if the breaker is on.

[@garciajuarez9677]

Hi how are you i contac you i live in mew jersey

[@JerseyMikeHVAC]

My contact info is on my channel page

[@edwardlara1011]

WTF.... HVAC technicians are not engineers this explanation is too long and detailed. I'm going to watch it a few more times to see if I can follow along. And mind you I have a B.S. degree.

[@JerseyMikeHVAC]

It's true, nobody looks at us HVAC technicians as engineers, but this is the level of understanding that is required to diagnose these things.

[@michaelbroadbent4703]

Your lack of education is exactly why we have HVAC techs changing parts all day that are not bad, you need to know this information to correctly diagnosis the defost system. If you are not constantly willing to learn yoru trade in great detail i believe you have picked the wrong trade to be in and i recommend that you please move to another profession that allows you to not have to know what your doing edwardlara1011