Chuck Schreiber

Having the SAME exact issue on the GTS right now.
If it is the fan, are there "cheaper" alternatives than genuine Porsche??

jon928se

Also worth bearing in mind that the fan controller has some fault sensing function - all I can think this is, is that it will sense too much current if the fan motor is stalled due to failed motor bearings and will switch off that fan - there is some interval after which it tries again.
This will make diagnosis difficiult as it will seem as if the non-functioning fan is getting no voltage (and correctly so) thus being a major red herring, when in fact the real problem is the motor bearings. The fans should spin easily with a finger and the rotation should feel smooth not lumpy.

Chuck S

That same fan motor is used in lots of GM (Vauxhall or Opel) cars in Europe in some cases with identical fan blades to the 928 and in others with a more modern fan blade design (same dia) which still fits. The only difference being the electrical connector - so if you get one from a breakers yard get the elec connector too.

Thinking laterally the Pontiac LeMans (88-93) might be a source as this was just a badge engineered version of the Opel Kadett/Vauxhall Astra that did use the same fan motor as the 928.

From my research if you can get the Bosch Part no. for the motor the last two numbers of the p/n indicate the electrical connector so that if the rest matches it's the same motor.

Paul Bakker

Both fans are controlled by a controller. This unit is next to the passenger seat. In my case I checked the non working fan by switching the wires and it did spin on the wireing of the working one so the fan is OK.
The 12V supply to both fans seem OK also so probable cause of my problem could be:

Defect in wireing between final stage unit and non working fan.
Defect final stage unit.
or
Defect controlling unit.

I found somebody who is willing to supply a working controller so I can swap them and see what happens.

Keep you informed.

Chuck Schreiber

Thx Jon!
Good info Paul.

Paul Bakker

Update:
If you disconnect plug from last stage and connect pin 1 & 5 the passenger fan should turn at 100%.
If you connect 4 & 8 the fan on driver side should spin for 100%.

In this way you can simply check wireing and fan operation from battery -> fuses -> fans.

Thanks Dr. Bob!

cwiert

I've determined that one of my fans (driver's side) is bad. So, I'll have to replace that. BUT.... this method to trigger the fans as quoted above isn't working for me, which makes me wonder if there's another underlying problem. I've pulled the wires off the temp sensor and jumped the 2 wires. After that did nothing, I tried jumping the 2 connectors on the temp sensor. That did nothing either. I tried both these while the ignition was on and the hood switch was closed and nothing happened. no fans went on. but when i come home after a spirited drive, the passenger side fan is on. So something is triggering the fan to come on, but I can't figure out what in order to make it turn on "on demand" even when the engine is cold.
Maybe I should just leave well enough alone and replace the 1 bad fan and be done with it.

dr bob

The reference to temp sensor should be to the temp switch on the top of the intake manifold. Connecting those two wires should cause the fans to run on slow speed while key is off and (on some cars) while the hood alarm switch is depressed.

cwiert

yup. that did the trick. thanks dr bob. although my car is one of the ones that require the key to be on.

dr bob

The intake switch and the AT temp switch specifically work when the key is off. Purpose is to help avoid a heat-soaked intake on hot restart. If the fan only runs with the key on you may have some more problems to chase. Did you depress the hood alarm switch?

auzivision

The fan motor offer is still good, but I don't think I'll have enough time to seperate it from the shoud and ship it before SITM. Are you going down?