Google Nest Themostat with mm-2 zone controller

[gdog1224]

I have a simple two zone AC/heating system that uses a honeywell MM-2 Mastertrol relay zone controller. There are two themostats. One with the heat-off-cool switch and a fan on-auto switch. 5 Wires to the first thermostat - Orange, Green. Blue, yellow red, and white. The first three are involved in switching modes and the fan override. The last three are the thermostat proper. The second thermostat is just three wire - white, red, yellow. I bought one google nest power connector (which I expected to need for the three wire thermostat. When I went to install the thermostat, the Google Home app said it was incompatible. Really? Any advice?

[maedacortez]

Hi gdog1224,

Thanks for reaching out. I understand that your Google Nest thermostat is saying it's not compatible. Don't worry, I'm here to help!

Before I can provide assistance, I need to ask some questions to better understand your situation:

• What type of Nest thermostat do you have? (If you're unsure, please visit How to Tell Which Nest Thermostat You Have.)
• What is the make and model of your HVAC system?
• Could you please send me a picture of your wire labels?

I look forward to your response.

Regards, 

Manuel