How to connect a Honeywell "round" 6-wire Thermostat to Google Nest Thermostat

[Mathism]

I need help to determine if my Honeywell thermostat can connect to Google Nest.  I have an older "round-style" Honewell thermostat (Air/Heat) 

Picture of thermostat wiring 

[CoolingWizard]

@Mathism , this is going to be tricky.  That is a a Honeywell Q539 subbase.  The R, Y, W and G are straight forward. The O and the B are not.  The B is normally wired to a Heating Damper. And the O is typically used to control a cooling damper.  Now to verify, does your system have heating and cooling dampers with motors? I have attached a picture of the subbase.

AC Cooling Wizard

[Mathism]

Cooling Wizard, thank your for your assistance!

Yes , my system does have heating and cooling dampers with motors.

[CoolingWizard]

Ok, um I need to review my NestPro manual to verify how, it at all possible, to operate two separate dampers in a single thermostat. Do you have access to a Volt Ohm Meter? 

AC Cooling Wizard

[CoolingWizard]

@Mathism , it took me a little while, but I finally found the manual for your thermostat. And what the system does is whenever your system mode switch is in heating, R is connected to B and W. And, when the mode switch is in cooling, R is connected to Y and O.  Now the Nest thermostat cannot do this.  What will be needed is to create a jumper in your air handler to connect the B wire to W and the O wire to Y.  The when the nest connects R to Y for cooling, the O will be connected in the air handler. And for heating, when the Nest connects R to W for heat, the jumper in the air handler will connect W to B.  

Do you have access to your air handler?

AC Cooling Wizard

[Alex_S]

Hi everyone,

I'm jumping in to ensure everything is good here. Have you seen CoolingWizard's response? Let us know of the answers so we could take a closer look at them.

We appreciate the help, @CoolingWizard!

Kind regards,
Alex

[Alex_S]

Hey there,

I wanted to follow up and see if you are still in need of any help. Keep us updated.

Best,
Alex

[Mathism]

Yes, I still need help! I would love to get this Nest up and running

[Mathism]

Hello, Thanks for the follow up.  (Sorry for my delayed response).  I should have access to the air handler . I will need to take a close look at my unit to see where it is located?? Would this be on the main unit itself or on the ducts coming off the unit?

[EmersonB]

Hello folks,

@Mathism, thanks for getting back to us. The location of your air handler depends on your heating and cooling system. Most often, air handlers are located in the attic, basement or a dedicated closet, and may closely resemble the shape of a gas furnace. In case you still have your manual, you can try checking it there.

I appreciate your response, Alex and CoolingWizard. 

Regards,

Emerson