Where should I start? There's another active thread discussing my engine compartment fan problem which I hopefully have the parts on order to fix (temp sensor and resistor).

Now it seems as though I've got an issue with the oil cooler blower. After charging the battery I started the car to see if the engine compartment fan still came on (it did when I shut the car off after running only a couple of minutes) but now I noticed the oil cooler blower (under front right bumper) was running and the car was just started. I've only heard this fan run when it was hot enough to open the thermostat and circulate oil.

Questions:

- do the engine compartment blower and the oil cooler blower share any components or are the discrete systems? They appear to be separate.

- there's a relay for the front blower. If it's bad would the fan not work at all or would the fan run all the time? The failsafe mode would be to run it all the time if the relay was bad.

Any other reason the oil cooler blower would come on as soon as I started a cold car? It's hot today (94F). Is this hot enough to get this blower to turn on as soon as the car was started?

Thanks again!

 

I'm getting really confused now.

Earlier I swapped the relay in position 4 (front blower oil cooler) with the relay in position 14 (front blower), they are the same part #, to see if the problem changed or moved. I started the engine and the oil cooler blower still ran as soon as I started the engine so I swapped them back. Afterwards, I went for a short ride and discovered the Air Conditioning compressor would not engage. Is the relay in position 14 for the AC? The map in the cover just refers to it as the front blower.

It's worn me down. I'm going to take it to the dealer and let them run diagnostics as there're too many variables coming into play for my simple brain to sort out.

 

Hi Buck,

Suppose you're taking the car to dealer, but I'll offer several thoughts anyway: <img src="graemlins/yltype.gif" border="0" alt="[typing]" />

--Yes, R14 is for the AC condenser fan, R04 is for the oil cooler fan.

Things that could make your oil cooler fan run when the oil is cold, ignition on:

1) Shorted relay. However, based on the results of Kim's suggested relay swap, this no longer seems likely.
2) Faulty oil cooler temperature sensor (resistance too low), which makes the CCU think the oil is hotter than it is.
2a) Faulty oil cooler temperature sensor (resistance very high), which makes the CCU think the sensor is disconnected.
3) Disconnected oil cooler temperature sensor (E.J.'s "fast-speed" trick).
4) CCU sending start signal to fan relay in error.

Based on what I know so far, #2 & 2a seem most likely. Then again, #4 is also possible, considering the problems you're also having with the rear blower. However, you don't want to rule-in the CCU until you've tried replacing the low $ components feeding the CCU, or running a donor CCU long enough to see if the problems go away.

The oil cooler and rear blowers don't share any common inputs, other than receiving their start signals from the $CCU$.

Did you mean to say the AC compressor wouldn't engage, or the AC condenser fan wouldn't run? Of course, the AC compressor is supplied by a completely different relay, located in the engine compartment fuse box.

Best of luck!

 

Buck,

I've got the same problem. My front oil cooler fan comes on with the ignition, no matter the temperature. I swapped the AC relay with the blower motor relay, and there was no difference in either of the two systems. I guess we'll have to hit Randall's DIY page and figure out where the oil cooler temperature sensor is and how to test it.

Will

 

[quote]Originally posted by Will:
<strong> I guess we'll have to hit Randall's DIY page and figure out where the oil cooler temperature sensor is and how to test it.

Will</strong><hr></blockquote>

Will, just replace it as a first check of the system. Takes about 15 minutes. You have remove the right front wheel and front section of fender liner and then you just have to unscrew it with a pair of pliers. It is near the top of the oil cooler. I don't remember exactly wehere it was located. Once you get the new part you will know what it looks like and then you just unplug the wire and swap the sensors. I think it was $19 from Phil at Suncoast.

Disclaimer: this was on my 1995, it may be different on an S model - although I don't see why it would be.

E. J.

 

Will/Buck,

You might also consider taking a room temperature resistance reading of the new sensor before installing, then taking a room temperature reading of the old sensor. If the old sensor reads something super low (1000 ohm or less) or super high (megaohms) at room temperature, you've definitely found your problem.

 

I broke down and took it to the dealer today. Being a Mechanical Engineer this electrical stuff baffles me. I've always considered Porsches mechanical masterpieces but I've always questioned their electrical designs. They sure seem to be overly complex.

I discussed the gremlins with the service manager and he doesn't think it's harness related but only time will tell. I did ask if they've had any experience with replaceing the harness and he said they've done four and they we pretty straight forward but time consuming. He did say they did have one nasty one. The owner went on a 3 week vacation and sometime during that period the harness shorted out and engaged the starter. Unfortunately the battery didn't die before the drive gear on the starter welded itself to the flywheel.

I update everyone when I find out what all wrong.

Thanks for all your input.

 

I suspect I also have a faulty oil cooler temp sensor, so I'm just going to replace both to be sure. But I have also noticed some unusual behavior coming from the rear engine fan, which is what got me looking through the archives in the first place. On a hot day, after parking the car in the hot garage, I heard a click and the rear fan came on. That's logical - but a few seconds later, I heard another click and the fan turned off. Then it came on again, then off, back and forth. Ideas?

 

I noticed Buck's other post on the rear engine fan staying on - that will give me plenty of things to try.