2 c wires - what to do?

[Vibo]

Hello my old thermostat has 2 wires (beige and yellow) in the c terminal (see photo) so I'm unsure what to do as it looks like the nest thermostat will only accept 1 wire in the c-terminal. Would appreciate your thoughts and recommendations. Thanks!

 

[jb76]

Hi - Layout for connecting a 5-wire HVAC to Nest is the following:
'W' (typically white wire) - controls Furnace heat - (confirm if you can on the furnace control board)
'G' (typically green wire) - control fan (unconditioned air)
'C' (can be blue or other color) - Common wire - 24V power to thermostat
'R' (typically Red) - controls furnace and supplemental power back to thermostat.
'Y' (typically yellow but can be other) - AC/Compressor control.

From your pic. - you should be able to match the current thermostat's wiring with the Nest - please reply back if you run into issues though.

j

[zoeuvre]

Hi folks, 

@Vibo, thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. If your old thermostat has two wires connected to the C terminal, and the Nest Thermostat only has one C terminal, kindly check on your HVAC control board where these wires are coming from. 

Thanks for your help, @jb76. 

Best,

Zoe