No Heat, No Fan, No errors on new install

[POPTOPP]

After replacing my 4-wire thermostat (R, G, Y, W with Rh & Rc jumped) all of the initial tests fail. Neither fan nor heat will start. No errors are indicated.  I checked the new gas furnace system board and there is a 5th blue wire connected which I believe is common.  There is a blue wire in the wall behind the old thermostat. I'm thinking next step is to complete that connection to see if that will do the trick.  But I don't want to fry anything.  Anyone out there who may know if this is a bad idea?

Thanks.

[Markjosephp · Accepted solution]

Hello POPTOPP,

It sounds like you're going through a bit of a challenge with your Nest Thermostat installation.

Connecting the blue wire to the common (C) terminal on the new thermostat should generally be a safe and logical next step. The common wire is often necessary for providing continuous power to the thermostat. Before making any changes, though, it's a good idea to turn off the power to your heating system to avoid any potential issues. Once that's done, connecting the blue wire from the wall to the C terminal on the thermostat and the furnace system board should help provide a common ground.

If you're unsure or uncomfortable with the process, it might be a good idea to reach out to a professional HVAC technician to assist you. They can ensure the proper installation and help troubleshoot any issues.

I hope your Nest thermostat gets up and runs smoothly soon. Let us know if you need more help.

Best regards,
Mark

[POPTOPP]

Thanks for your confirmation. This did solve the issue.

[Jenelyn_O]

Hey POPTOPP,

Thanks for the update! We're glad to hear that the issue is now resolved. Please feel free to create a new thread if you have any questions or concerns, as we'll be willing to help.

I appreciate your input, Mark.

Cheers,

Jenelyn