C Wire Not Detected

[sandramarybrown]

Yesterday I had an On Tech technician install my Google Nest Thermostat. I didn’t realize it didn’t come with a wall plate to cover blemishes from the previous thermostat. So I ordered one. The tech showed me what to do to install it myself. I just put the wall plate on, but now it’s saying the C wire is not connected. It was working yesterday. I tried stripping the wire, making sure it was connected properly, factory reset the thermostat, removed it, and re-added it to my account. What should I do next? Thanks in advance. 

[Patrick_Caezza]

@sandramarybrown 

Did you turn the power off on your system before you did anything?

If you didn't, the you blew the fuse on the control board in the furnace/air handler

[sandramarybrown]

@Patrick_CaezzaI did turn it off. My switch is on the furnace itself. The tech showed me where it was at. Should I replace the fuse on the control board to see if that helps? 

[Patrick_Caezza]

@sandramarybrown 

You can try that.

While you are there take a look at the terminal block and verify that the C wire is connected there.

Post a picture of the terminal block here if you can.

[sandramarybrown]

@Patrick_Caezza

I looked up on how to change the fuse on YouTube, but I’m not seeing where to do it on mine… I do see the c wire there, though. 

 

[sandramarybrown]

 

[AxelD]

Hi Sandramarybrown,

Thank you for replying and providing those photos. They're very helpful.

As you noticed, the C-wire is connected, but the fuse hasn't been changed. Please change the fuse and see if that resolves the issue.

Let me know once you've done this.

Regards,
Axel.