Some time the mane blower won't shut don,and kip blowing cool air if appen the furnace won't start again I just shut the furnace to cool off turn it on after 20 minutes is good to go for days wy the probleme.the furnace name I tink is rpj2 the contol box in front ove the big blower is furnaral 90 inter- city products model 50a50-131