C wire e79 error

[Sonar427]

The thermostat says the c wire isn’t connected. But I’ve tested the c-wire and it has power. 

I’ve double checked all the wire connections to the base. 

Any advise is welcome.  

 

[Patrick_Caezza]

Post a picture of the original thermostat's wiring.

Looks like you have both the Rc and Rh wires installed. Do you have separate cooling and heating systems?

If you do, the C wire must come from the cooling system and not the heating side.

[Sonar427]

Thanks. You're correct i have separate heating and a/c. 

I need to have my HAVC guy come and connect the c-wire to the a/c instead of the boiler (they are two separate systems). Hopefully that will solve it. In the meantime I replaced the nest with an old, conventional thermostat just to keep the heat working (it's chilly here in the Northeast).

I have to say, this has been a royal pain to troubleshoot. 

And why the initial installation instructions didn't require a c-wire. The Nest ran for about 3 months before it died because of no c-wire. 

[Jake]

Hey Sonar427,

I am sorry for the trouble you have run into. I know this is not an ideal situation. Please let me know if you have any issues once the pro comes out, as I would be happy to assist.

Best regards,

Jake

[Jake]

Hey Sonar427,

I wanted to follow up with you, and see if you were able to get the HVAC pro to come out and take a closer look. Please let me know if they were able to resolve the issue, or if you have any questions from here.

Best regards,

Jake

[Jake]

Hey Sonar427,

I want to ensure you are good to go, and everything is working properly. Please let me know if you are still having trouble, as I will be locking the thread in 24 hours due to inactivity.

Best regards,
Jake

[EdwardT]

Hi folks,

@Patrick_Caezza, thanks for the help!

@Sonar427, how's it going with your Nest Thermostat? Still need our help?

Thanks,

Edward

[Jake]

Hey there,

I wanted to check in, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake