C-wire heating but not cooling

[Tman518]

I installed the nest before winter and had no issues with the connectivity which included C-wire. When I attempted to turn cooling on I kept getting a power disconnect/ wifi disconnected status. A/C would restart wait 2 mins and do the same thing. I removed the C-wire and it purs like a kitten. What issues am I going to run into? Will this cause any problems down the road? or do I just need to connect C-wire during heating season?

[ZeroZero]

I had exactly the same issue.  It seems a common problem.  My C wire (blue) doesn't have any voltage.  Once disconnected from Nest thermostat, cooling works, heating still works (my heating is gas).

I've traced the wire to the AC unit control board.  The blue wire is actually not connected to C terminal on the control board.  It appears splitting from the red (R) wire.  The Y (yellow) wire at my thermostat appears actually connected to the C terminal on the control board going through the external unit.  Anyway, instead of messing around the existing wiring, I would probably just replace the thermostat batteries more often.

[Patrick_Caezza]

@Tman518 

Look in the furnace/air handler and see if the C wire is connected to the C terminal.

Never trust the wire colors as there is no standard

[Jenelyn_O]

Hi everyone,

Thanks for reaching out. I just want to check if you were able to see the response above about checking your furnace if the C wire is connected to the C terminal. Also, please share with us the photo of the wires that are connected to your control board. 

I appreciate your help, @Patrick_Caezza.

Best,

Jenelyn

[EmersonB]

Hello everyone,

We wanted to follow up and see if you are still in need of any help. Please let us know if you are still having any concerns or questions from here, as we would be happy to take a closer look and assist you further.

Thanks for answering, Patrick_Caezza and Jenelyn.

Regards,
Emerson

[Dan_A]

Hello again,

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.
 

Cheers,

Dan