this SPST switch provides critical high-limit protection by interrupting the circuit when system pressures exceed safe operational thresholds

The sensor uses a Nickel-Iron Balco element with a reference resistance of 1000 ohms at 70

"HERM" for the compressor

replacing it with a new 29388 control board typically resolves this failure

including the ST9120C2010 and ST9141A1002 series

Heil Quaker ICP 1150886 Board Els PW 17895 this SPST switch provides criticalThe Heil Quaker ICP 1150886 Fan Timer Board is a critical electronic control component designed to regulate the operation of the burner and the circulating fan in oil furnaces. This board is technically identical to the Honeywell ST9103A1028, providing a direct swap replacement for aging or faulty furnace controllers. Engineered for robust performance, it manages the timing sequences for both heating and cooling cycles, featuring a fixed 30 second fan