aux fan operation (thermo switch question)

[scottinAZ]

ok, due to my redoing the fan system in the car, I need to know about the workings of the thermo fan switch.

According to the ETM, the low temp side closes (turns fan on) at 91c, and the high side closes at 98c. what I need to know, and is pretty important for my operation is does the low side OPEN when the high speed closes?

If I am to have the smaller fan (1000cfm) kick on at say 91, and the larger fan (2400cfm) at 98, it makes a difference to me at least if the small also keeps running

just for shits and giggles, I am using the factory ETM temps, I will be installing an E36 fan switch (with its lower operating temps) with the fans. I just need to know electrically if both will run using this setup, or if I have to juggle some relay inputs.

[nando]

I'm pretty sure it must, but this would be pretty easy to check with a DMM and a pot of boiling water.

[scottinAZ]

the reason for asking is that I dont have a spare, and the original is still installed in the motor. THe etm is ambiguous on this issue, as there does not show an interlock between the parts of the switch that would open the low side when the high side is activated.

Looks like I need a spare switch......

[nando]

I'd just buy the lower temp one from the E36 M42 (80/88c) anyway.

[jrobie79]

I'd just buy the lower temp one from the E36 M42 (80/88c) anyway.

do you have a part number for this nando?

[jlevie]

The low and high temp switches are exclusive. When one is closed the other is open. A bit of rewiring will necessary for both switches to keep the fan on.