fan control

I need to know how to make this work. I have a oil cooler with a fan that has a thermal cuppler at comes on at a higher temp then i like it to.  I would like to hook a switch so i can turn it on when i like to and sill have it hooked up to the cupler.

Do you know where the relay that powers the fan is located?    Do you know if the thermocouple switches power or ground to the relay?

the thermocuple is power  there is no relay its run right to the battery

It it's an actual thermocoupler then there would have to be an interface, as thermocouples work down in the mV range. 

Do you have a schematic of the system?  Is this an OEM system or an aftermarket system?

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Kevin Pierson

I am thinking that he has a thermal switch.  How big is the fan and do you have any idea how much current it draws?    If it is a small fan and you have room to mount a switch that will handle the current of the fan, simply apply fused power to one side of the switch.  Connect the other leg of the switch to either the fan's power wire or to the output side of the thermal switch. both of these points are electrically the same, I just gave you 2 options incase one is much easier to get to than the other.

Its aftermarket fan draws 6 amps the the part on the box says thermocoupler but a thermal switch would make more sence.iI was tinking of runing off a switch to the output side but just dont wont to see smoke.

There will be no smoke.