Industrial 12338599 Engine Cooling Fan Thermostatic Switch

The 12338599 thermostatic switch automatically engages the engine cooling fan clutch at a defined coolant temperature in HMMWV M998-series vehicles and Hummer H1 diesel installations. This 24 VDC, temperature-activated normally open switch closes its electrical contacts at the preset threshold to activate the engine cooling fan clutch when cooling demand rises. It mounts in a threaded engine coolant passage, senses engine coolant temperature, and is designed for GM 6.2L and 6.5L diesel engines. Commonly installed in AM General HMMWV M998, M1025, M1038, and Hummer H1 vehicles, it supports reliable cooling during military operations, heavy towing, and off-road use. Identifiers include Part Number 12338599, Alternate Part Number 5579285, and NSN 5930-01-237-7322.