OEM electric fan

#1

The oem fan has a resistor/switch that controls the fan.
Can I connect the fan directly without the switch so everytime I start the car the fan starts?
Is that controlled by the thermostat as well?

#2

On my 635 race car I shorted the low speed switch for the fan to stay on all the time. I then wired the high speed to a switch on the dash. Worked fine.

Michael O.

#3

low fan speed can be activated by AC button, and high speed is activated when detected temp is around 95C or so (IIRC). You can just live your AC button to ON position all the time or permanently wire it to "ON". Or wire it that always comes on to high speed, or add separate switch with OFF, Low, High and maybe AUTO (auto being current functionality). Do a quick search on the forum I think it was discussed couple of times IIRC

Igor

#4

Thread back from the dead!

I’m wiring up my new SPAL fan. I wanted to use the factory wiring. There is a larger round connector with I believe 3-4 leads on it that went to the aux. fan. I’d like to be able to use the A/C button to trigger the fan when needed. Is that circuit a protected one? Is the button on the interior wired to a relay? The wire size indicates it must be, but I want to make sure before I wire the power/ground leads directly into the old harness.

#5

As noted, this has been discussed in previous threads. Search auxillary fan. In short, if you push out the AC on button from the dash, the yellow lead is the fan on lead. Splice into yellow wire and run this to a fan relay (can get from autozone, about $20) with the relay wired to the battery power source under the hood (passenger side access where starter power lead comes from). Then wire directly to the Spal fan.
Ed

#6

I made mine switchable by splicing into the wires to the temp sensor in the radiator. I then ran the wires into an unused switch (fog lights I think). Now when I push the switch it completes the circuit and thinks the coolant temp is too high, which turns on the fan. It will also still turn on the fan automatically if the coolant temp really is too high.

Matt

#7

I have the fan relay and considered that. However, I can easily splice into the factory fan wiring near the coolant resivoir where the connector is without really cutting anything on the existing wiring harness.

The question is whether or not the stock fan is relayed in the stock wiring system. I have already stuck some wires in there and the fan runs fine. Unfortunately, I don’t know if it is relayed and don’t want to permanently wire it that way unless I know for sure. I’d rather not have a “fire sale.”

I do already have the relay if I need to install an external one.