Four Seasons 36509 Engine Cooling Fan Switch - Upper

Temperature Switch for Radiator Mount Cooling Control

Four Seasons 36509 is a radiator-mounted engine cooling fan switch built for temperature-based fan control. It uses a 2-terminal black rectangular female connector and an M16 x 1.50 male thread for direct radiator mounting.

With an open fan setting and an operating range of 188 degrees off to 197 degrees on, this Four Seasons Temperature Switch line part is made to meet or exceed OEM requirements. It is a direct-fit temperature switch for service work on select BMW 328is and Nissan 200SX applications.

Key Features

• Brand: Four Seasons Temperature Switch
• Part number: 36509
• Radiator mount design for engine cooling fan control
• Black rectangular female connector
• 2-terminal electrical connection
• M16 x 1.50 male thread
• Fan open/closed configuration: Open
• Temperature off at 188 degrees and on at 197 degrees
• Meets or exceeds OEM specifications

Product Details

Four Seasons 36509 is a temperature switch used to trigger radiator fan operation based on coolant temperature. The switch mounts in the radiator and provides a direct electrical signal through its 2-pin connector when the specified temperature threshold is reached. This makes it a practical replacement for vehicles that rely on a radiator-mounted engine cooling fan switch to manage operating temperature. It is listed for 1996-1997 BMW 328is and 1987-1988 Nissan 200SX, including radiator mounted engine cooling fan switch service on those applications. If you are searching for a BMW 328is temperature switch or a Nissan 200SX radiator fan switch, Four Seasons 36509 is the matching part number to reference.

This part cross-references Marmon Ride Control A6626 for the same application.

Common Problems This Part Can Address

• Cooling fan not switching on at the correct temperature
• Cooling fan staying on longer than expected
• Intermittent radiator fan operation caused by a worn temperature switch
• Incorrect fan cycling that can affect engine temperature control
• Fault codes or drivability concerns tied to fan switch signal loss

Installation Notes and Tips

Confirm the radiator mount location, M16 x 1.50 thread size, connector style, and temperature range before installation. Match the 2-terminal connector and female plug orientation to the existing harness, and verify the replacement switch is intended for the same radiator-mounted application. For fitment-specific searches, this part is commonly referenced for 1996-1997 BMW 328is and 1987-1988 Nissan 200SX cooling fan service. Always compare the original switch specifications to Four Seasons 36509 before installation.

Quality Assurance

Four Seasons lists this temperature switch as meeting or exceeding OEM requirements, supporting OE-style fit and function for the specified applications.