Nest Thermostat - Cooling mode turns on A/C.... Heating mode also turns on A/C...

[och-tamale91]

TUE 26 APR

Replaced Honeywell TH8320U thermostat (top photo) with Nest Thermostat (bottom photo). Upgraded software to version 1.1-11. Internet connection is fine. I have a conventional gas furnace.

Well, in a nutshell, if I turn the A/C on, it operates normally; if I turn the heat on, it also acvtivates the A/C , so I am not getting heat. I already tried swapping the Blue and White wires on the Nest (suggested from a previous thread), but it did not work.

Any thoughts would be appreciated....

[CoolingWizard]

Your current nest thermostat does not support multi-stage heating and cooling. You need to switch to a Nest Learning Thermostat in order to be able to support your two-stage compressor.  The proper wiring for the Nest Learning Thermostat in your system is as follows:

Rc - Red Wire (Power 24VAC)

Y1 - Yellow Wire (Compressor Stage 1)

Y2 - Blue Wire (Compressor Stage 2)

G - Green Wire (Fan Relay)

C - Orange Wire (24VAC Power Neutral)

W1 - White Wire (Heating Relay)

If you want to temporary test your system, using the thermostat you have you will need to wire it this way:

R - Red Wire (Power 24VAC)

Y - Yellow Wire (Compressor Relay)

W - White Wire (Heating Rely)

G - Green Wire (Fan Relay)

C - Orange Wire (Power 24VAC Neutral)

Cap off the blue wire for now. Your system should work but you will not have your Stage 2 of cooling. 

The AC Cooling Wizard

[och-tamale91]

THANKS Cooling Wiz!... I've ordered the Nest Learning Thermostat.... Will I need a C Wire?

[CoolingWizard]

In your old thermostat, the Orange wire is the Common wire.  Whenever you can have the 24 V AC common wire it’s always better..

AC Cooling Wizard

[Patrick_Caezza]

@och-tamale91 

The Google Nest Thermostat is compatible with your thermostat as it does support 1-stage heat and 2-stage cooling. System types that are Nest-compatible 

Your problem is you have the blue wire going to the W terminal when it should be going to the */OB and set as 2nd-stage cooling. The white wire should go to the W terminal, not the */OB terminal.

With it wired the way you currently have it, when it calls for heat, it turns on the 2nd-stage of cooling instead of the heat.

[CoolingWizard]

@och-tamale91 I need to apologize for misstating.  Your current thermostat can handle the 2-stages of cooling.  Put the blue wire in *OB and when asked about wiring, configure it as Stage 2 Cooling. 

AC Cooling Wizard

[och-tamale91]

Thanks Patrick & Wiz... I appreciate your respective reponses and help here.

Putting the blue wire to *OB... easy....

But configuring to Stage 2 cooling... really not sure how to do that. I have been to seetings on the thermostat, and there is no option; I searched for intrcutions and YouTube videos on the subject, and found nothing.

Any additional insight would be helpful.

Thanks again!

[Patrick_Caezza]

@och-tamale91 

The Google Nest Thermostat must be reset to factory defaults and set up again.

This time when the Google Home App asks you which wire you have, you need to select these wires from the options.

W/W1, Y/Y1, G/G1, R, C, and Y2

[Markjosephp]

Hello folks,

I wanted to ensure that everything was covered here.
 

Thanks for sharing your expertise here, @CoolingWizard and @Patrick_Caezza. Big help!

@och-tamale91, I hope you've found the answer you're looking for. If you're still in need of assistance, feel free to let us know.

Regards,

Mark

[Markjosephp]

Hi och-tamale91,

I wanted to see if you still needed help. Please let us know if you have any other questions or concerns.

Thanks,

Mark

[Jenelyn_O]

Hi there,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

I appreciate your help, @CoolingWizard, @Patrick_Caezza, and Mark.

Best,

Jenelyn

[CoolingWizard]

I do not know the Nest Thermostat as well as the Nest Learning Thermostat.  Basically, you need to go into SETTINGS > EQUIPMENT > WIRING  (I think).  Once there you need to look for a way to change a wire assignment.  You need to make * is set to Stage 2 Cooling. Perhaps @Patrick_Caezza knows that model better than I.

The AC Cooling Wizard