Gas Furnaces Re: L4064B Fan & Limit Switch The L4064B controls the on and off operation of the heating unit’s fan motor and provides high limit control of the main burner. It is suitable for all types of forced air heating systems. The L4064B’s bimetal sensing element turns fan on and...

York Gas Furnaces: PUDD Re: Heating Sequence of Operation These furnaces use either a Robertshaw SP735 or White-Rodgers 50E47 hot-surface ignition controller. Sequence of Operation 1. Call for Heat On a call for heat, the thermostat sends 24V to the "W" terminal. 2. Inducer Motor...

York Gas Furnace: PUDD Re: Ignition Lockout Customer reports that the furnace sometimes stops working. They can get it to work again by turning the thermostat or power off and back on. Small Control The PUDD uses a White-Rodgers or Robertshaw Hot-Surface Ignition Control. The control's...

York Gas Furnaces: PUDD Re: No Heat / Won't Come On This condition is generally reported two different ways by the customer: "The furnace won't do anything." - Indicating that there is no activity from the furnace on a call for heat. "The furnace makes a noise, but it never blows-out hot...

York Gas Furnace: PUDD Re: Burners Fire then Shut Off The furnace goes through a normal ignition sequence, but several seconds after ignition the burners shut off. Qty Possible Causes (From Most to Least Likely): 2 Dirty flame sensor Bad Ignition Control ...

York Gas Furnace: PUDD Re: Burners Cycling Off / Burners Won't Stay On The furnace burners fire and run for several minutes, then the burners shut off and the furnace goes through another ignition sequence. Qty Possible Causes: 2 Pressure Switch Limit Switch ...