Help please.Engine cooling fan not working
 

New relay. Resistor in duct and cooling fan temp sensor. STILL not coming on when engines hot. AC works great and fan starts up when ccu is dialed to heat. Oil temp gauge pegs out every once in a while but goes to normal temp after a few taps on gauge. Is it related to rear cooling fan ? Don't want to kill my engine on these hot oklahoma days. Thank you all for help. John

That gauge problem would spook me from driving the car until it was resolved. It might be nothing, but like you say, why risk doing permanent damage.

As far as the fan problem, are talking about the aux fan back in the engine compartment, correct?

If so, did you jump the terminals where the relay goes to see if you could force the fan on in low or high speeds?

Check the connection on the back of the gauge. I've never had to, but read that the instruments simply pull out of the dash and are held in by the rubber trim ring.

As for the oil cooler fan, do you have battery voltage at pin 30 of the R04 oil cooler relay socket. If not, check the 30A fuse #2 in the fuse and relay box.

Yes I did jump it. It worked in high but not low speed when jumped. ( Rear fan ) I have not tried this since new resistor and relay installed. I tried turning the key to start the fan about an hour after I put those in and the fan worked ? Maybe resistor or relay needed time to recognize each other ?? Hope it keeps working because I'm stumped if it doesn't. Thanks for your responding. Jb911

Thanks Traveler. I jumped the oil cooler fan. It works in low and high. Tried pulling the gauge. Extremely tight. The gauge face does just pull out not screw out right. Even the rubber cord isn't wanting to budge ? Should I just force it more ? Don't want to break it. Thanks for your knowledge. I've only had this car since November. Still feeling my way around it. John

I'm assuming it is your gauge connection because you stated tapping the gauge gets it to work.

Check out this diagram.

Use some silicone spray at the joint between the gauge and rubber ring.

Do not force it. Patience!

Thank you. I will do that. Hope I can be as much help to someone someday as you all are to me now. Thanks again. John

I don't think there are 2 speeds for the engine cooling fan. Mine will come on after 5 minutes and run for 3-5 minutes after I park it in the garage. Only when it's really hot. I've never noticed anything but a high speed blast which cools the engine quickly.

Engine cooling fan working when running but even after a 40 mile trip in 98 deg heat it doesn't stay on when I shut car off. Thought it would for a bit ? Is this normal ? Thanks. John

Engine off, it will only turn on (low speed) if the temperature sensor reaches 75C (167F) and it will turn off when the temperature goes below 70C (158F).

You can remove the sensor and put a heat gun to it to raise the temperature to test it. Or you can simply ohm the sensor out: 20C (68F) = 12.5K ohm, 45C (113F) = 4.4K ohm.

Traveller you're a genius ! Why didn't I think of the heat gun !? Just tried it and it worked as it should. Didn't realize it needed that much heat to come on. Thanks. John

Nope, just someone who has the Porsche electrical wiring diagrams and Adrian Streather's "Porsche 993 - The Essential Companion" book. The latter will just shorten your search for explanations of system operation. That book is worth getting.

Check your Private Messages for a link.

If you come across a cheap 10-turn 20K ohm pot (not a trim pot), those can be hooked up in place of the NTC (negative temperature coefficient) sensor for testing purposes.

Turn it up and down; watch the fan go off and on. Measure the resistance as well if you wish.

Mine has been working this way also, on a really hot day (this is Phoenix, after all) I shut the engine off but the blower fan will not run when it seems as though it should.

I'll have to try the heat gun on the sensor.