Low temp cooling fan problem

[beerad1111]

I have a situation with my cooling system. Both fans come on when straight wired, and when I jump the fan thermo switch on the radiator the high speed fan setting works properly. When I jump the other wire nothing comes on. I am replacing the thermo fan switch and need to know what else could keep that low temp setting from turning on the fans.
Thanks for the help.

[geniushanbiao]

First when you said you straight wired the fans did you try both high and low? Each fan has 3 terminals of which one is GND, one is high and one is low. You should try both to make sure the fan works properly. Last year when I replaced my fans one of the them was still working at high but not working at low.

If you already tested the fans properly, then measure voltage at low terminal when jumping the thermo switch's low terminal. If you don't see voltage there then the fan control unit is bad. Replace the fan control unit or take it off to repair(I think it's just a bad soldering which is a common problem on NBs)

Originally Posted by beerad1111

I have a situation with my cooling system. Both fans come on when straight wired, and when I jump the fan thermo switch on the radiator the high speed fan setting works properly. When I jump the other wire nothing comes on. I am replacing the thermo fan switch and need to know what else could keep that low temp setting from turning on the fans.
Thanks for the help.

[IndyTom]

I used to have a problem with my Fans turning on as soon as I turned on the ignition without even turning on the engine.
For me it was the 112C temp switch that was faulty. After replacing it the fans returned to normal operation.

Home Page > Search > 357919369F > ES#248948 2-Pin Thermal Switch - 112C* - 357919369F

[beerad1111]

Thanks for your reply. Yes I jumped the hot and ground at each fan lead plug they both worked fine. However when I jumped the thermo switch plug only the hi speed worked. What do you think about that situation?
Thanks for your help.

[IndyTom]

Originally Posted by beerad1111

Thanks for your reply. Yes I jumped the hot and ground at each fan lead plug they both worked fine. However when I jumped the thermo switch plug only the hi speed worked. What do you think about that situation?
Thanks for your help.

I think the Thermal switch is defective. Those 2 pin switches are known to go out over time. I would replace it and see if that solves your issue.

[geniushanbiao]

Originally Posted by IndyTom

I think the Thermal switch is defective. Those 2 pin switches are known to go out over time. I would replace it and see if that solves your issue.

I think the thermal switch he's talking about is the 3 pin one on radiator which sends signal to fan control unit.

[beerad1111]

Your right it is a 3 pin switch and I replaced it didn't fix the problem. Any more suggestions I'm pulling at straws now.
Thanks for the help.

[geniushanbiao]

Originally Posted by beerad1111

Your right it is a 3 pin switch and I replaced it didn't fix the problem. Any more suggestions I'm pulling at straws now.
Thanks for the help.

As I said, your fan control module is probably bad. Pull it, tear it down and do some resoldering or replace it(which is not cheap).

[beerad1111]

Is the fan control mod. the one mounted under the battery box?

[IndyTom]

Originally Posted by geniushanbiao

I think the thermal switch he's talking about is the 3 pin one on radiator which sends signal to fan control unit.

No, the regular coolant switch is a 3pin but the one I am talking about is the 112C thermal switch which is a 2 pin.

Here is the link to the part.

Home Page > Search > 112c Thermal > ES#248948 2-Pin Thermal Switch - 112C* - 357919369F

It is located in the Green Circle:

[IndyTom]

Originally Posted by geniushanbiao

As I said, your fan control module is probably bad. Pull it, tear it down and do some resoldering or replace it(which is not cheap).

I would try the 2 pin Thermal switch first. Also there are some aftermarket Fan control Modules that are around 50 bucks on Amazon.

http://www.hansautoparts.com/1J09195...rolModule.aspx

http://www.amazon.com/Module-1J09195...9240541&sr=1-6

If you do order a Fan Control Module make sure the Part number is the correct one for your application.