1

New home and trying to change old thermostat. New DIYer for electrical and HVAC. No C Wire however it does have 5 wires. RH, RC, Y, W, G.

Attached is the schematic on the actual unit. I am unsure how I would be able to wire a new thermostat without a C terminal. I have a Honeywell adapter coming in however I don’t know which wires to attach it to. Not having a control panel with terminals made this confusing.

The schematic shows only 4 wires but to my understanding and per the photos. RC and RH attach to the R line making it all one for the thermostat.

The white wire with 5 internal lines runs directly to the thermostat. The brown wire with red white and us used green come from outdoor unit.

Any help would be appreciated!

enter image description here

enter image description here

enter image description here

enter image description here

Improve this question
1
  • The Brown is the C wire
    – DIY75
    Commented May 8 at 7:36

1 Answer 1

Reset to default
3

The (appliance-internal) Brown wire is your C wire.

To bring the C wire to your room thermostat, re-purpose the blue wire in the white cable running to the thermostat to be the C wire. Disconnect it from the red wire(s) and connect it to the brown and white wires (where the white is running to your outdoor unit).

Improve this answer
1
  • 1
    If you repurpose the blue wire, which is correct, your old thermostat may need it's Rh and Rc terminals joined with a short piece of wire. Your new thermostat will come with a metal jumper or switch that you should set that way if it's not the default.
    – jay613
    Commented May 8 at 10:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.