Cool setting blows hot air

[Evilyne]

New installation of Nest thermostat. 2 identical AC units outside and upstairs and downstairs thermostats inside. Wiring is identical upstairs and downstairs. Upstairs unit blows hot air when I test cool or have it set to cool. Both Nests work correctly if I pop them off and put them downstairs. Upstairs works fine if I reinstall the old thermostat. Is it just incompatible?

[Evilyne]

 

[kiltguy2112]

I had this happen at my house. The problem turned out to be a shorted wire between the tstat and the outside unit. Need an HVAC mechanic to find it though.

[Patrick_Caezza]

Post a picture of the original thermostat's wiring.

[Evilyne]

 

[Patrick_Caezza]

This should be wired like this

Blue - C to C

Green - G to G

Yellow - Y to Y1

White - W to W1

 Red - RC to Rc (jumper to R not needed)

[Patrick_Caezza · Accepted solution]

The original thermostat's wiring only has five wires, but your Nest wiring has six wires. Where did the extra orange wire come from?

[Evilyne]

Oops, wrong old thermostat. 2 house problems. I installed the stupid things last fall and then forgot about the problems until the weather started warming up and it looks like I deleted all the pics of the old thermostat off this phone. Disregard that photo, sorry. 

[Patrick_Caezza]

No worries, Post a picture of the terminal block on the control board in the Furnace/Air handler instead. It will provide the same information.

[Evilyne]

Just in case anyone was curious... it was wired wrong. White wire is now in W2 and orange got moved to O/B because it is a heat pump. Downstairs only appeared to work because the coolant had leaked out, so it couldn't make hot air to blow and it was just blowing room temp air around on either setting. It just hadn't gotten hot enough outside for us to notice yet. Both AC units will have to be replaced due to salt damage #beachlife

[MelbaDT]

Hey folks, 

Thanks for checking on this and for responding, Patrick_Caezza. 

kiltguy2112, thanks as well for sharing and we're glad that everything is now good on your end. 

Evilyne, we're also glad to hear that you've had it sorted out and thanks for keeping us in the loop of what resolved it. Feel free to let us know again if you have more questions. 

Best, 

Melba

[K_Lawson]

I am experiencing the same issue, but I’ve had the same Nest Learning thermostat installed since April 2020, and only recently had an issue with the cold setting blowing hot air. Last summer, the cold setting worked fine. Then the heat worked through the fall and winter without issue. Now, the cold setting blows hot air. Nothing has changed. We have the same heat pump, the wiring wasn’t changed, and we haven’t had any other issues.  I tried changing the OB settings to troubleshoot, but that didn’t fix the issue. I tried resetting the thermostat, and that didn’t fix it, either.

Do any of the Community Specialists have insight as to why the Nest that was working fine for almost two years would suddenly just start blowing out hot air on the cool setting?

[Evilyne]

Yeah, based on my problem and solution, I'd say you have a coolant leak and probably need a new AC unit. Sorry for the bad news.

[MelbaDT]

Hey folks, 

Thanks for responding, Evilyne. 

K_Lawson,I understand how you feel about this. Overtime, wiring weakens and some parts of our HVAC system corrodes, so it is best to have an HVAC technician or a local pro check on your system. 

Best, 

Melba

[MelbaDT]

Hey there, 

Checking back in should you still have some questions about this. 

Best, 

Melba

[MichaelHFarren]

Nope! I had mine checked by a HVAC TECH. Nothing wrong with my heat pump at all. Even confirmed with hooking up an old thermostat. The nest simply cannot last more than 2 years. 

[MelbaDT]

Hey there, 

I understand and sorry if you feel that way. Rest assured that we'll also pass your feedback along to our team. 

Best, 

Melba

[MelbaDT]

Hi, 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Best, 

Melba

[MichaelHFarren]

I didn’t want to get rid of my nest, but I had to. I just had another technician come on this past Friday, and we proved the nest WILL NOT switch my heat pump into cool mode. I have the Honeywell thermostat on, and it’s working perfectly. When I called google nest, I really really hoped that they would send me a new unit. Not just say, well, your warranty is expired now. Also , since my nest broke 8 months ago, and I needed a brand new base, my warranty should have started again. This is the problem. This is what bothers me most. Google has not stood behind their product. So anyone else with this problem, IT IS THE NEST!! (Unless you wired it wrong of course) 

[Ryan_G]

Hi MichaelHFarren,

Thanks for being here in the Google Nest Community.

I'd like to jump in here and check if you're still experiencing the issue on your Nest Thermostat. Let me know by replying to this thread.

Best regards,

Ryan

[MichaelHFarren]

Yes!! I had to take the nest off, and bought the Honeywell. I no longer use the nest because it does not work! Certified HVAC TECHS confirmed it, then the new thermostat proved it completely 

[Ryan_G]

Hey folks,

Thanks for visiting the Google Nest Community. 

Since this thread hasn't had activity in a while, we're going to close it to keep content fresh.

If you have additional questions, feel free to submit another post and provide as many details as possible so that others can lend a hand. 

Hope this helps!

Kind regards,

Ryan