I have an electric heat/air unit. When I turn the heat on it only runs for about 7 sec. then shuts back off. It will kick off and on until I turn the unit off at the thermostat. It won't stay on long enough to feel if it is warm air or not. Please help! Is it the thermostat or something else?

My thought, it's a cheapie, and it overheats. Or if it has a filter, then try cleaning it out.