E79 error when furnace is switched on

[SimpleUser125]

 

Hi,

Can someone please help me figure out this issue. When I turned off the furnace main power switch, the c wire is showing power connection, but not the rh (both wires are detected). Once the main switch is turned on, the c wire is detected and showing no power, but the rh is now showing power connection (e79 error). My question is whether I’ll be able to set up my nest by unplugging the c wire to bypass the e79 error? And by doing so, will the best charge itself through the rh wire?

thanks!

[Houptee]

Try moving the Red wire to Rc and see if that fixes the issue.

 Also you should check at the furnace to see if the Blue wire is actually attached to the C terminal in the furnace.

[Patrick_Caezza]

The red highlight means there is a problem with the C terminal, not that it has power.

THe e79 error code means there is a physical wire detected in the C wire terminal, but it isn't detecting voltage. This usually means the wire that is inserted into the C terminal isn't connected to anything at the far end or there is a break in it.

Look at the terminal block on the control board in the furnace/air handler and see if that wire is connected to anything.

[aatienza]

Hey SimpleUser125,

Checking in — we hope you've got the answer you're looking for. Let us know if you have more questions in mind.
 

I appreciate the help, Houptee and Patrick_Caezza.

Thanks,

Archie

[aatienza]

Hey there,

I just wanted to follow up to see if you still need our help. Please let us know as we would be happy to answer any questions you may have. 
 

Thanks,

Archie

[aatienza]

Hello there,

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
 

Thanks,

Archie