We had a new AC system put in this summer. I turned it off as the weather moderated, but even though the thermostat is set to off, the AC runs. It also looks like the heat does not run. It was chilly last night and I turned the thermostat to heat on and set the temperature appopriately, but no heat came on.

The AC guy came back once to fix the AC thermostat issue and told me I needed a knew heater. Can someone tell me what is going on?

Thanks

Since I am not there I would suggest you check or have someone check the thermostat and associated wiring first. Then if that fails to solve the problem check the heater for proper operation and repair/replace defective part.

You may need to know a little more about HVAC. A good place to start is the sticky at https://www.askmehelpdesk.com/heatin...ons-58313.html

I think there is a mix-up in the wiring at the t-stat. Use the red for heat, the green for fan, the yellow for condenser (AC) and the white for C common. The Rh and Rc can have a jumper wire between them at the t-stat. The connections at the heater control board need to correspond with the connections at the t-stat. You may need to remove the cover at the heater to check the terminals. DO NOT FORGET to SHUT OFF THE POWER. Many have a plug at the unit and most have safety switches on the door, but you still need to trip the HVAC breaker !