So I am putting my Aux Oil Cooler back in place and had ordered a thermostatically controlled fan, but I don't remember how it was hooked up(yes I did do it a couple years ago) .

there are the 2 wires, a positive and negative coming out of the fan, and this has to pass thru the thermostat switch. What I am wondering is , it looks like the positive goes directly to the battery, and the negative passes from the ground point or negative on battery thru the switch and then to the fan, OR is it the other way around?

Phil

this picture was taken before we dropped the motor and disconnected it all- the bottom right you see a red button, this is the thermostat control - wiring goes thru this to the power source- but which way?

I was always taught to use the negative on the thermostat.

But one disadvantage of sending the positive directly to the battery instead of switched power is that the fan can run after the engine is shut off.

Not sure the re is any advantage to running the fan after the car shuts off.. I would change the positive to switched power.

I would run off a switched power source not directly from the battery.
If the t-stat failed it could run the battery dead.

Also makes sure you have a fuse in line some where to protect your wiring and car.

Jim

so some internet research on this trying to come up with the exact wiring recommendations, but the simple answer is taking the + (blue wire) from fan to the switch and on to the fuse and then battery. Black is ground and goes to what ever we decide is ground, negative on battery or body ground.

will test tonight and see how it works out!

Agreed for sure to have fuse there and it was before, and I will look at doing this to a switched power source but I like that directly it runs to continue to cool the cooler when car is sitting and turned off.

Phil

Here's the simplest way to connect the oil cooler fan and thermostat. Notice the 15A fuse in series with the thermal switch. Any wire from the battery should be fused else you could melt wires or worse start a fire. The thermostat could be on the negative side of the fan towards ground and the colored wire directly connects to the fuse and battery.

If you go with this simple arrangement, I would not recommend running the 12V power from the ignition switch as the heavy fan current will go through the ignition switch. You could pick up switched power on the relay board from the power supply relay which is switched on via the ignition switch.

Click to view attachment


Going one better to a switched fan control using a standard relay is shown below. I have this arrangement on my oil cooler fan on my 930. The heavy lifting of powering the fan is done by the relay while the thermostat only powers the coil of the relay.

Switched power comes from the ignition switch or better yet uses the power supply relay on the relay board to power the relay coil.

Click to view attachment