Cold air when on heat

[Jackiep1970]

We have had our thermostats 3 years (1 in living room and 1 in the master bedroom). The end of last winter, the one in the bedroom started blowing cold air when on heat. It worked fine all summer on air conditioning. Today I turned it back to heat and it’s cold air again. I have restarted and then reset the thermostat with no change. Any ideas? It worked great for 2 1/2 years. 

[RenzJ]

Hi Jackiep197,

Thanks for posting here in the Google Nest Community. We're sorry for any trouble this may have caused you. Let's check this out. There are two possible reasons for the vents to blow out cold air, even if you’re calling for heating. One is the Nest Learning Thermostat O/B settings. You can change the settings by following the steps below:

1. Press the ring to open the Quick View menu.
2. Choose Settings .
3. Go to Equipment, if it shows you the O wire, change it to B and check for a result. If it shows you B, change it to O and check for a result.

The second possible reason is if the reverse valve of your heat pump system is broken. On this part, we suggest contacting a local technician or Nest Pro technician by going on their website: OnTech.

Let us know how it goes.

Cheers,

Renz