Industrial 12338599 Engine Cooling Fan Thermostatic Switch

Description:

The H1 Humvee M998 Thermostatic Switch 12338599 is an engine cooling fan temperature switch used in military vehicle cooling systems to automatically engage the engine-driven fan clutch when coolant temperatures reach a specified threshold. Commonly installed in AM General HMMWV M998 series vehicles and Hummer H1 models equipped with the 6.2L or 6.5L diesel engine where reliable engine temperature regulation is required. Maintenance teams, military vehicle restorers, and fleet operators use this switch for cooling system repairs, replacement of failed fan switches, preventive maintenance, and restoration of military vehicles.

Applications:

The H1 Humvee M998 Thermostatic Switch 12338599 is commonly used in AM General HMMWV M998, M1025, M1038, and Hummer H1 vehicles. The 12338599 configuration senses engine coolant temperature and activates the viscous fan clutch or engine-driven cooling fan when necessary, helping prevent overheating during military operations, towing, off-road driving, and heavy-duty service.

Technical Specifications:

• Manufacturer: AM General
• Model / Part Number: 12338599
• Alternate Part Number: 5579285
• NSN: 5930-01-237-7322
• Product Type: Thermostatic Switch / Fan Temperature Switch
• Switch Type: Temperature-Activated Normally Open Switch
• Function: Activates engine cooling fan clutch based on coolant temperature
• Operating Voltage: 24 VDC vehicle electrical system
• Mounting: Threaded engine coolant passage installation
• Sensing Medium: Engine coolant
• Compatible Engines: GM 6.2L and 6.5L Diesel
• Compatible Equipment: HMMWV M998, M1025, M1038, Hummer H1, and related military vehicles
• Operating Principle / Function: Closes electrical contacts at a preset temperature to engage the cooling fan
• Application Environment: Military, off-road, and heavy-duty vehicle cooling systems

Common Replacements:

• AM General 5579285 Thermostatic Fan Switch
• ACDelco D1808A Cooling Fan Temperature Switch
• Standard Motor Products TS-158 Thermostatic Switch