[tbeale]

Symptoms are; burners ignite and after a short time they shut off. The blower never comes on. If I turn the blower to full-time on, the heat works fine. Should the module have 24 vac when the blower is full-time on (it does)? I believe the control module is bad.

Do I check the 24 vac voltage when the unit is set to auto to determine if the module is bad?

[JonesHVAC]

In theory the 24vac has nothing to do with the blower motor other than it is needed in pre heating sequences in order for the blower to come on... for ex: thermostat calls for heat --> closes circuit completing 24vac to control board, series of events within control board --> inducer motor comes on expelling any gases in exhaust --> ignitor glows --> gas valve opens --> flames --> limit opens --> blower comes on. There are some other steps in there but are not needed for this.

Turn thermostat off and shut power down. Clean your flame sensor with a piece of fine grade sand paper careful not to break it. It is the little probe looking thing up near the burners. Turn power back on and turn thermostat back on to call for heat. Let me know how that works out for you.

[tbeale]

The Heil Fan Control Timer was bad.