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How do you decide if the unit is defective?

Community Member

I have 2 Nest 3rd generation thermostats- one for downstairs and one upstairs (2 HVAC units). The upstairs unit died with no warning a few weeks ago. Won’t hold a charge when I try to charge it with the USB port. Bought a 24 v transformer and the unit wouldn’t recognize the c wire. When I brought the downstairs unit upstairs and switched it out everything worked fine. Help? 


Platinum Product Expert
Platinum Product Expert


How do you have each Nest wired?

How did you wire the external transformer to the Nest?

Post pictures if you can

To ensure that I see your reply, please tag me using @Patrick_Caezza