York Gas Furnace: P3DH/P3DN Re: Lockout Codes Red Light Status Description On Faulty Control Rapid Flash Low Flame Sense Signal 1 Lockout Caused by Flame Sensed 2 Pressure Switch Stuck Closed 3 Pressure Switch Stuck Open 4 High Limit or...

York Gas Furnace: P3DH Re: Flashing Code 4 CODE 4 = High Limit or Blower Limit Open There are three limits on this furnace: Primary Limit Auxiliary Limit Blower Limit If any of the three limit controls open, the burners will be de-energized and the air circulation and vent blower will be...

York Gas Furnace: P3DH Re: Flashing Code 5 Flashing Code 5 = Rollout Switch Open Other symptoms associated with a Code 5: Blower and Inducer Running Continuous No Heat Qty Possible Causes: 1 Rollout Switch Tripped Bad Control Board CHECKOUT: 1. Check...