Hello,
Heat is not working, help I need advice, this what I have discovered.

Thermostat = Auto, Heat; I hear a small blower fire up below the house and it runs for about 2-3 min. and then nothing happens.

Thermostat = On, Heat; Same as above.

Thermostat = On, neither Heat or Cool is selected; the main blower turns on and circulates the air. When I select heat while the main blower is on the main blower turns off and I am back at what happens above.

Any advice is greatly appreciated, I am very versed in electronics so testing components should not be to challenging if I know were to start.

Thanks for your help.

Anton

Brand and EXACT model number?