How can I tell if my home has a C-wire?

Here’s how you can check if you have a C-wire: 

• Check thermostat wiring 

To check for thermostat C-Wire, turn off your HVAC system and go to your thermostat. Remove its faceplate. You will see various connections to their terminals. Look for a black or blue wire connected to the C terminal.

In some cases, the C-Wire will probably be tucked away in the wall behind your current thermostat. To find it, remove the thermostat faceplate and unscrew the backplate. Next, pull out all the wires. Search for the wire bundle and look for an extra black or blue wire, or one labeled ‘C’. 

• Check your control board

Go to your HVAC control board and look for a wire attached to the C terminal. Note down its color (mostly blue or black) and go to your thermostat. Check for the same colored wire. 

In some situations, your HVAC control panel has a C wire terminal, but there's no wire attached to it.

If there’s no wire connected to the C terminal on either your thermostat or the control panel, your home likely doesn’t have a C-wire. A C-wire adapter is helpful in this case. It provides a dedicated power source to the smart thermostat.