My Nest Tstat won't turn on my AC, it blows hot air instead. I paid a HVAC tech for a service call and he tells me that the tstat is bad (wasn't sending the signal to the cooling unit). He wired the condenser to work temporarily but says to replace the tstat, otherwise I won't be able to use the heat during the cold season. How do I get a replacement?
Sounds like this is the first time that you are using the A/C site since you installed it.
Have you tried changing the reversing valve control? You can give it a try as it won't hurt anything.
If your system starts to blow cool air when your Nest thermostat is in Heat mode (or if it blows warm air when it's in Cool mode), change the settings for orientation of your heat pump.
I am having the same issue, the problem is with the Nest itself. There is an (apparently prevalent) issue that causes the O/B wire to not become energized such that the heat pump reversing valve will not activate. Saw online a tech guessing there’s a bad FET controlling the O/B wire signal. Confirmed at my unit, with the unit set to both heating and cooling mode, and with the orientation both set to O and B. Never voltage on the O/B wire. Jumping the O/B and R together at the compressor turned on the cooling right away. Replaced the Nest with a Honeywell stat and all worked as it should. You (and I) have a faulty product.
Hoping to get something. Mines only 5 months old and the cooling didn’t work on the first day I tried to switch over. Started a warranty claim, they were saying I’d have to pay for a new unit and send back my old one, then they’d reimburse. Phone call got cut off before I was finished talking but that doesn’t sound the best to me…