After installing a Google Nest, my furnace heats until it reaches the correct temperature, but if it sits, the controller light turns off and I need to turn the breaker off and then back on in order for the furnace to kick in. The controller light turns off, but does not flash as far as I have seen. I have switched back to the original thermostat, some basic Honeywell one, and it works fine. There is a C wire connected, though I had to add that and I'm not sure if it's totally legit. Currently the C-wire is connected at the T terminal.

My furnace is a Lennox G14 series (I'm not sure which model exactly).

I am fine using the old thermostat, but I am bummed because I was looking forward to automating this stuff. Thanks for any help!

Wire diagram

Thermostat wires connected to furnace

Controller with light on

  • can you show us the problem maker (Nest) wiring
    – Traveler
    Commented Nov 11, 2022 at 18:54
  • where did you get the C wire from ?
    – Traveler
    Commented Nov 11, 2022 at 19:10
  • @Ruskes I never took a picture of the Nest wiring, but all the wires went to their respective letters (i.e. Red => R), and the blue wire went to C. I pulled the new wire with the blue included awhile ago, and the original thermostat is using it now. Commented Nov 11, 2022 at 21:04
  • I am interested in helping you, but need more information. What was connected on Nest ? R, W, Y, G, C ?? What would shut down the furnace ? The Limit switch ! / why ?
    – Traveler
    Commented Nov 11, 2022 at 21:35
  • @Ruskes R, W, Y, G, C were all connected. The furnace would reach the correct temp, turn off, and then most times not come on again, with the inside temp being 5-10 degrees below the setting. That's when I would have to cycle the breaker, which would turn the furnace on immediately. Commented Nov 11, 2022 at 21:54

1 Answer 1


The solution that seems to be working so far is adding a 1kOhm 5W resistor between W and T, that being the call for heat voltage. After contacting Johnson Controls, I was redirected to an engineer at Baso (which now owns this particular model of Johnson Control) told me that older controllers sometimes expect more of a load when heat is called for, and newer controllers have these built in.

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.