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944 Fan Potential Problem

M

MOLE

New member
Hello All

I have just entered the world of Porsche ownership with a 1989 944 S2.

I am really pleased with my new car but there is an issue that I am not sure about.

What temperature should the radiator cooling fan/s come on at?

At the moment, when I drive the car from cold, 1 of the fans comes on once the temperature gauge gets to the 1st line (about 1/3rd of the way up the gauge). This seems very low to me and means that the one of the fans (passenger side from memory) is running for most of the time that the car is being driven.

The fan is not running from start up and when I pulled out the relay the fan stops which suggests that the relay is working and the temperature sender/sensor must be working to a fashion if the fan only kicks in once the car has started to warm up.

I know these cars can suffer from fan relay and temperature sensor problems that can cause the radiator fan/s to run continuously even with the ignition off, but this this is not seemingly the problem I am having. Is the fan coming on at too low a temperature or is this the norm for this car?

Thanks for the advice in advance.
 
Hi there !

Yes, You're right to suspect some issues with the fans and/or thermostat. My understanding from discussions and the wiring diagram (as far as I can tell regarding the fans/electrics the turbo & S2 are identical ?) is that both fans should run at the same time, two speeds depending on the temperature.

I believe that at 88c the slow speed comes on and then at 98c the high speed. This is kicked in by the thermostat that is in the side of the radiator with a three pin connector. I believe that both fans have separate fuses though so this might be a good place to start.

The only other element to factor in, is the AC - when you switch this on both fans should come at low speed.

Hope this helps,

Yours

Chris
 
I wonder are mine playing up too then. Mine comes on low to start with then as the car warms up they switch to warp speed and never kick off again the whole time im driving the car
 
The fans on my old S2 used to stay on with my old radiator, as it could not get rid of the heat quickly enough.

If your fan cuts in at the sencond line (1/4 way up) I would look into the fan switch being the issue. They are not too pricey from Porsche (or least they were not 3 years ago...). At least then you can rule out one suspect.
 
Oh and if the fans are on at full speed, say after some low speed maneouvering, they should go to the slow speed to conserve battery power when the ignition is turned off, then go off altogether after a few minutes.
 
ORIGINAL: 924nutter

I believe that only cars with A/c have the three terminal temperature sensor.
Click to expand...

My S2 had a 3 pin sensor and that came from the factory without AC. When I was testing things by shorting them out as per Clark's Garage guide, one terminal is for the low speed on both fans, with the second being for the high speed. It is possible that only the Turbos and S2s came with the 3 pin sensor.

As stated earlier in the post, the low speed comes on when the car hits 88 degrees (or on an AC car whenever the AC is set to turn on). The high comes on when the car hits 99 degrees Centigrade :).
 
Mole

A thought for you based on the previous posts - it could be that your radiator is past its best ? Rads get clogged up both internally and externally - you'll be amazed at the cooling difference putting a new rad on makes. If your car has never had a new radiator it might be worth the investment together with a new temp switch.

Yours

Chris
 
Thanks for the responses.

I think I shall replace the temperature sensor/ fan switch in the radiator first. As has been mentioned here, these are quite cheap and so a good place to start. I understand that these can be bought with different temperature ranges so maybe I shall buy one with a high temperature trigger to see if that makes the fan come on at a higher temperature.

With regard to radiator condition, is it worth disconnecting the radiator and flushing it through?

Also, can anyone shed any light on why only one fan is running and not both?
 
Yes, it is worth flushing it through, although if it does turn out to be partially blocked, no amount of flushing will fix it.
 
Mole

Like I said ISTR that the fans have separate fuses if not relays - worth checking these as a starting point.

Chris
 
Just went out to the car and check the fuse box. The fuse for the 2nd cooling fan had indeed gone.

I replaced it an let the car run until the temp gauge got to between 1/2 and 2/3 of the way up, at which point BOTH fans kicked in. Thanks for the advice, particularly Chrisg.

I hope all the work I do on my 944 in the future is this painless, but somehow I doubt it will be.
 
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