I have a Trane XE 80 heater and the main blower will not start. The burners will light, the exhaust fan comes on but the main blower fails to start. Got any ideas?

Have you tested the blower motor?

Try turning on the auto switch on the thermostat to ON. That should make the blower run all the time. If that does not work then I suspect the motor is defective or the blower relay on the circuit board might be bad.