topic Re: Heating when in cool mode in Nest Thermostats

Heating when in cool mode

Rigorh — Tue, 18 Jul 2023 05:27:34 GMT

My current thermostat (Honeywell, probably doesn't matter) wiring is as follows:

R - Red

Y - Yellow

W - Blue

G - Green

Yes, only four wires. I followed the instructions from GoogleHome and it seems that it "worked" and got everything connected. I wired it as follows:

Y-Yellow

W-Blue

G-Green

R-Red

The issue is when I put it in cool mode, I get the heater on. We are in the middle of summer here in Arizona, so heater is not good. Please help. You can tell my experience is limited, but I think this means I have a heat pump, but I just don't know where to place cables.

Re: Heating when in cool mode

Rigorh — Tue, 18 Jul 2023 05:32:01 GMT

This is what I had:

This is how I connected it:

Re: Heating when in cool mode

CoolingWizard — Tue, 18 Jul 2023 05:42:17 GMT

@Rigorh , to help you we need to know if you actually have a Heat Pump system. The wire you have in W, is actually OB. Move the wire to Nest *OB, set as a type O heat pump. After that your Air Conditioner will work again.

AC Cooling Wizard

Re: Heating when in cool mode

Rigorh — Tue, 18 Jul 2023 05:49:07 GMT

First of all, thanks for replying!!
I have this kind of thermostat, could I still set the type O heat pump? Or does it have to be the other kind?

Re: Heating when in cool mode

CoolingWizard — Tue, 18 Jul 2023 06:06:55 GMT

When you put the blue wire in OB, the nest will detect it. The default is to set to O type.

AC Cooling Wizard

Re: Heating when in cool mode

Rigorh — Tue, 18 Jul 2023 19:38:34 GMT

OK, understood.

Is there a possibility that this burns a fuse in the machine? It is on the roof and I currently don't have access to it. If there is a high chance for that to happen, I think I will just leave the original one.
Again, thank you so much for your help!

Re: Heating when in cool mode

CoolingWizard — Tue, 18 Jul 2023 20:22:30 GMT

@Rigorh , the only way you might blow a fuse is if the wire that is attached to the C terminal comes in contact with the R wire. Remember that on a thermostat and a conventional HVAC control system, the R wire is the 24VAC power from the transformer.

AC Cooling Wizard

Re: Heating when in cool mode

Rigorh — Tue, 18 Jul 2023 22:08:06 GMT

OK, i changed it to OB and still got warm air. What else do I need to change?

Re: Heating when in cool mode

CoolingWizard — Tue, 18 Jul 2023 22:15:51 GMT

@Rigorh , ok, need to try changing the Heat Pump mode to B type. To do this on the nest display go to SETTINGS > EQUIPMENT > CONTINUE > CONTINUE > HEAT PUMP. Then move the checkmark to B and save.

AC Cooling Wizard

Re: Heating when in cool mode

Rigorh — Tue, 18 Jul 2023 23:38:44 GMT

OK. I want to write this in case somebody else has this problem.
Since I had already set the thermostat (with the wires Y, W, G, and R, see picture posted above at the beginning of the thread), it was not letting me change the Heat Pump mode to B type on the thermostat. So, I had to factory reset the thermostat and go over the process again. What changed now, is that instead of selecting in the GoogleHome App the just mentioned wires, I selected Y, G, R, and *OB. This time, the Heat Pump activated the mode to B automatically and solved this issue.

Thanks for your help, I really appreciate it!

Re: Heating when in cool mode

zoeuvre — Tue, 18 Jul 2023 23:47:27 GMT

Hi Rigorh,

Awesome! I'm happy to hear that everything has been sorted out. Since we can now consider this one complete, I will be locking this in 24 hours if we don't hear back from you again. Feel free to start a new thread, and we'll be happy to help.

Thanks for all your help, @CoolingWizard.

Cheers,

Zoe