Thermostat Switch for Honda Rancher 400 TRX400FA TRX400FGA 2004-2007

Thermostat Switch for Honda Rancher 400

This thermostat switch replaces OEM part numbers 35250-HN4-670 for Honda Rancher 400 models TRX400FA and TRX400FGA, controlling when the cooling fan engages to keep engine temperature in the proper range.

Overview

This thermostat switch for Honda Rancher 400 models is a direct-fit replacement for the factory temperature sensor that triggers the cooling fan. It installs at the engine thermostat housing and sends the signal that tells the fan when to turn on and off. Built for riders and mechanics servicing their own machines, this thermostat switch restores consistent fan operation on TRX400FA and TRX400FGA models.

Built For Performance

• Direct replacement for OEM part number 35250-HN4-670
• Threaded body fits the stock thermostat housing without modification
• Bi-metal thermal element switches the fan at the designed activation temperature
• Sealed electrical connector resists moisture and dirt intrusion
• Heat-resistant housing survives repeated thermal cycling
• Plug-in terminal design matches the factory fan circuit

Fits These Machines

• for Honda Rancher 400 TRX400FA (2004-2007)
• for Honda Rancher 400 TRX400FGA (2004-2007)

On-The-Job Use

• Replacing a failed fan switch that leaves the engine running hot
• Restoring cooling fan operation during slow trail riding and mud work
• Routine maintenance on high-hour Rancher 400 utility quads
• Fixing overheating that only appears when the machine sits idling

Specs At A Glance

Good To Know

Q: How do I know the thermostat switch is the problem? A: If the fan never comes on and the engine runs hot at idle, the switch is often the failed part rather than the fan motor itself. Testing the switch with a multimeter as coolant temperature rises confirms whether it closes the circuit.

Q: Does this switch need any special tools to install? A: No special tools are required beyond a wrench for the threaded body and access to the wiring connector. Draining some coolant before removal helps avoid spillage at the housing.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.