My residential roof heater/air conditioner unit does not shut-off the fans when the heater is switch off at the controls. Setting the thermostat to 0-degrees or opening the circuit at the control won't turn off the heater fan, only the gas will shut off. Shutting off the main power supply is the only way to turn it off. Turning it off and on does not help, no clicking is heard from the relays. Normally, it is timed for 1-3 minutes before the fans shuts off, but it doesn't. When it does shuts off, I can hear a click from the relay. The air conditioner works fine.What could be wrong with the circuit?
Thanks