Just installed new Honeywell RTH7600. All wires are correct and the unit displays fine. The issue is that heater and AC do not turn on at all. I even put the fan to ON instead of AUTO and that does not turn on either. not sure what the issue is.

THe unit will display "Heat on" or "Cool on" to indicate that something should be happening. I hear a click from the unit, but nothing actually happens.

So far I ihave tried power cycling at the circuit breaker. But im thinking about first re-seating all the wires and second reinstalling the old unit to make sure that still works and that my ac/heater didn't just go out at the same time somehow.

  • Do you have a heat pump? If so, is the thermostat set up to work with a heat pump? Did you check the furnace/air handler to make sure it has power? Do you have a multimeter, and know how to use it? – Tester101 Jun 20 '15 at 16:03
  • As far as I know its a gas furnance. dont have multimeter. I read online that after reset the circuit breaker it can sometimes takes up to 30 minutes for the units to reset and start working again....so im gonna wait it out. Also read to check the fuses. I Just re-seated all the wires. – Raymond Holguin Jun 20 '15 at 16:16
  • Without a multimeter, you're not going to much troubleshooting. – Tester101 Jun 20 '15 at 16:47
  • I got a multimeter, what do I test? I put the old unit back on and still nothing is working anymore. It was working great before i decided to swap out the thermostat this morning. I took a picture of all the wires and their locations beforehand, so i know exactly where everything is supposed to go. – Raymond Holguin Jun 20 '15 at 18:52
  • after reading some issues others have had ive seen mentioned of having to turn off breakers for indoor and outdoor units? supposedly the outside breaker isn't enough and i was supposed to turn something off inside as well? If i was supposed too...i didn't and don't know wwhere that is – Raymond Holguin Jun 20 '15 at 19:00

If you swapped out the thermostats with the power on, you could have shorted out the transformer. Best case is a blown fuse, worst case is a blown transformer. Do you have a C wire at the thermostat? If so, test AC voltage (VAC) between R and C. You should get between 24 and 30 volts.

The furnace breaker should be in the main panel, or there will be a servicemen switch near the furnace. If a fuse is blown, it will be on the control board inside the furnace.

  • FYI for anyone with similar issue, the Furnace breaker was labeled as "FAU" on the main panel. – Raymond Holguin Jun 21 '15 at 19:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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