Auxiliary Fan Thermal Switch/Seal

1990 XJ-S Coupe (US Spec, 5.3L V12)



Auxiliary Fan Switch (Part Number EAC 2510)

Auxiliary Fan Switch Seal (Part Number C37990)

Adjustable Wrench


The component is sometimes called the “Fan Switch”, “Coolant Switch”, “Radiator Cooling Fan Switch”, “Auxiliary Fan Switch”, “Fan Thermal Switch”, “Electric Fan Switch”, etc.  On a stock car, the Auxiliary Fan is the Electric Fan.


This switch will turn off the Electric Fan when the car is shutdown and the coolant temperature drops.  There are other components that play a role in turning the fan on/off, including the Air Conditioner Compressor, the “Blue” Pektron Diode Pack, etc.  There is a lot of information about the circuit on the Forums and in “Experience in a Book”.


The switch is mounted on the front of the water pump, near the center of the front of the engine.  It has two wires connected to it via spade connectors – carefully unplug them first.  The coolant needs to be drained or else it will come pouring out of the hole when you remove the switch with an adjustable wrench (at least 1 & 1/8”).


I got the Switch and Seal from (their part numbers IN102121 and IN101337 respectively) for $16.66.  Contrary to what you’d think, the Seal goes on the outside of the switch – providing some protection for the connectors.  Put the “flange” of the Seal towards the Switch.


Auxiliary Fan Thermal Switch and Seal

(Viewed from Left Side - Front of Engine, Near the Middle)



Questions/comments: Email me.