The A/C was not running when I changed the batteries. My electronic thermostat is Honeywell Rev. Honeywell Thermostat Heat Not Working After Battery Change By Jon Posted on June 18, 2020 Most thermostats only use the batteries to power the thermostat itself, LED display. Make sure they are in the right way and spring tension is good. And when it is time to troubleshoot, most of the solutions are simple for the owner to execute. If spring tension is not good you may not be making contact to both ends and not completing the circuit.

Honeywell's programmable thermostats are designed to be easy to use under normal circumstances. 5-96 After I change the battery, it not work again :( Please help me!!! It has rested for an hour after re-setting and turning the breaker off/on again. have to have an HVAC tech troubleshoot, and possibly replace the transformer. Set it back to 76 degrees. Thank you very much! ! If your Honeywell programmable thermostat flashes "Batt Lo," you simply need to replace the battery. Still not working. No wires are loose, I only removed the cover, not the entire thermostat from the wall. To test if it is not the thermostat causing issues cross the white and red wire to test furnace, red and yellow for outdoor unit and red and green for indoor fan

Tried lowering the thermostat to 50 degrees, still nothing.