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Help With Odd Nest Power Connector Wiring

Kirete
Community Member

Hi y'all,

I have 2 nest thermostats and an HVAC system with no zones - one thermostat is for heating and the other for cooling. Both complain about no power / C wire and therefore don't connect to wifi and burn through batteries. I got a Nest Power Connector but the wiring on my control board doesn't make sense. Control board has C, G, R, and W. Heating thermostat has W and R. Cooling thermostat has R, G, Y.

So, at the thermostats there's no C as there is at the control board, but there is a Y for the cooling one, but no Y at control board. Switching the control board C to Y made the cooling compressor not turn on. 

 

How should I wire the Nest Power Connector?

Thank you! 

3 REPLIES 3

Kirete
Community Member

Here are pics of the system: 

PXL_20220130_205445668~2.jpg

PXL_20220130_205527483~2.jpg

PXL_20220130_205554919~2.jpg

Ryan_G
Community Specialist
Community Specialist

Hey Kirete,

 

Thanks for reaching out and including the photos to your post.

 

Looking at the photos, it seems that we're missing one wire for the cooling. The yellow wire is for the common wire as it is showing from the main control board. What I am curious about is the blue wire from the first photo, you could check if it's connected on the main board. That possibly be the wire for the common and the yellow is for the cooling. Once you checked it, it looks like your system can be controlled using only one thermostat. 

 

I hope to hear from you soon.

 

Regards,

Ryan

Kirete
Community Member

Thanks for the reply Ryan!

The blue wire on the cooling thermostat was plugged into G on my old one (before I switched to Nest). The cooling works in the current setup, which has always confused me since there's no connection to the Y at the control board. Truly my only practical problem is the lack of power to the Nests. 

I remain stumped as to how to connect the Nest Power Connector given this setup. Might a need a pro to come check it out? Hoping to avoid for cost & COVID.