Electric Fan Relay & Harness Kit 40 Amp with 185F Degree Thermoswitch

Application: This kit suits wiring an aftermarket electric fan on hot rods, street rods and performance builds where a temperature-controlled fan switch is needed rather than a manual override, using a 3/8 inch NPT sensor to trigger the fan automatically off coolant temperature.

Size/Spec Context: The 40 amp circuit breaker protects the circuit while the 50 amp relay handles the switching load, giving headroom above typical single electric fan draw. The 1/2 inch NPT reducer is included for radiators or housings with a larger threaded port than the 3/8 inch sensor.

Construction Note: Kit includes 10-18 gauge wire, crimp terminals and hardware, with easy to follow instructions for a complete DIY install without needing to source additional wiring components separately.

Fitment Note: Universal kit suiting most single electric fan setups. The temperature switch turns the fan on at 185°F and off at 170°F, a fixed threshold rather than adjustable, so confirm this switching point suits your cooling system before ordering if you need a different activation temperature.

What to Pair With: Commonly paired with a single electric fan and, on dual fan setups, the corresponding dual relay harness kit in the range instead of this single fan version.

Practical Buyer Tip: Because the temperature switch is a fixed 185°F on, 170°F off setting, this suits standard cooling setups; if your engine runs a lower thermostat or you need adjustable switching, check the Derale adjustable controller options in the range instead.