When the switch is on heater and auto the thermostat will click but heater won't come on. When flipped to ac and auto, comes on, or on, the fan blows then also. Can hear the fan blowing on ac or on but will not blow on heater. When opening the inside unit can hear a clicking like the fan is trying to come on, but can't.

Electric,, gas,, oil?, does it have a brand name or a model number?

Electric... EB 15B