I have a Rheem gaspack unit. When the cooling system is on, the system runs fine (and cold, I might add). However, when the heating unit is on, the blower will only run for a about 10 sec. then switch off for about a minute. Then switch on for 10 sec, etc. I believe that gas remains on during even when the blower is not running. Is this a relay switch problem? I believe I was once told the unit I have has two seperate relay switches for heating and cooling. I don't think it's the thermostat.