Most failures are caused by restricted airflow due to dirty filters or obstructed ductwork

allows contractors to fine-tune system response for compressors

What is the purpose of the manual lift stem

As an official part from Nortek Global HVAC

As a factory-direct component

Williams P323663 Safety Switch 340155-7026 Most failures are caused byThe Williams P323663 Safety Switch is a critical OEM vent limit protection component designed to maintain the operational safety of your gas fired heating equipment. Engineered as a safety limit switch for Williams wall furnaces and vented room heaters, this part features a high precision sensor that triggers at a fixed 200F temperature. When the exhaust gases in the vent reach this thresholdoften due to a blocked flue or inadequate draftthe switch