I turned on my air conditioner today and it came on, but so did my heater. This did not happen last summer. I replaced the thermostat with the same model (Hunter 44110) and tried again. Still happens. Also happens when I turn the unit to Heat, the Air Conditioner blows at the same time. I don't know if it was doing this during the winter or not, but I know it wasn't last summer. What could have happened to make both the Heat and Air run at the same time?

Do you have electric or gas furnace, or oil,, heat pump,, what? Needed to know to help you