Chris Layton

Another lurker comes out of hiding =) I used to own a 1989 944 Turbo S but the wife got tired of it so now she has a beautiful 1990 944 S2 coupe (http://test.misterx.org/ourcars/1990s2/ for those that like pics) with 55K orginal miles. We have been going through the car fixing minor things when a interesting issue popped up with the radiator cooling fans.

I dug around in the archives and found similar problems to what I have but nothing that was exact. Here is a quick breakdown of what is going on :

- Rad termo switch just changed out to a lower temp version (part # 951 606 48100). It was changed as we belived the low speed wasnt working properly. Issue with varying speed started right after change of switch.
- Shortly after this change the fans started cycling between low and high speed (about 10 seconds on low then 10 seconds on high never staying at one speed). This would occur with A/C on or off, sometimes even when the motor was cold from sitting over night, but never with the car off and key out.
- Changed out switch (same part #) no change
- Changed out the Fan relay no change
- happens when A/C is on or off.
- Doesnt happen with car off (key out)
- Does happen with car off but key in (not all the time just sometimes)
- Does happen on ocassion with car off , key in, thermo switch unplugged, a/c off.
- Always cycles between low speed and high speed. Never stays on one or the other.
-As to be expected unplugging the fan relay always stops the fans.
- I think its doing this while moving (50mph+) but its hard to check


Any input would be appreciated

gman1868

Mine did the same thing and went through the same troubleshooting. What finally helped was replacing one of the two large resistors under the fuse box, one of them was bad.

That didn't completely cure the problem, it doesn't do it anynore when the a/c is off. After that I gave up, it's a club race car so who needs a/c, right?

Chris Layton

You were dead on ! Found one of the wires had come off one of the resistors ! Crimped the connector down for a better connection and it has been working since.

Thanks for the tip !

BrettC94

Thank you for your perfect description of this problem. I now know that I'm not alone. But I'm having a problem...can't find the resistor on my '89 S2 cab. I've pulled the fuse box and spent about an hour looking up from the floor and can't find anything that resembles a "large resistor".

Any guidance that you could provide on the location of these resistors would be appreciated.

BrettC94

Found it! It seems to be in a different location depending on which day the car came off the line.

gman1868

A different location? Oh boy.

TO find the problem with my car it cost me $900.00 in parts and labor before they figured it out. Then, a little over a year later, a guy hit me during a club race and now the car is sold.

BrettC94

I'm sorry that you got wrecked. I know that it's a risk you take on the track, but it still has to suck.

I'm still having my fan cycling problem.

Once I eventually found the resistors I tested them out. Unfortunately they were both fine. The Wiring to them was corroded. I cut back the leads and did my best to tin the ends and then solder a pigtail to the resistors. So now I don't know if its a corroded wire harness issue or if I need to dig into the relay. I'm the type that likes to completely eliminate one possibility before moving on to the next. So I guess that I'll replicate the wiring harness to go back as far as I need to find good wire.

Any recommendations? I can't afford to put $900 into finding this problem.

BrettC94

As I mentioned in my previous post, my resistor is fine. I then replaced about 2 feet of wiring, still no fix. I then jumped 12V to V1 and V2 individually. When I did this, fan motors 1 and 2 (respectively) turned slowly. This confirmed that they resistor circuit was fine and the problem was in the relay itself.

BrettC94

I got lucky on e*bay and found a $35 relay and avoided the $180 for a new one. Problem solved!!!

BrettC94

If you're reading this because you have a similar problem.....good luck. Compared to other p-car problems, this one is not that bad and you can logically figure it out.