ataman

I bought a 993 Porsche year of 1995 Carrera 2 Manual Drive last month. Sometimes, after stopping the engine, the cooling fan (I guess) is still working and it never stops unless I unplug the wire from heat sensor. My car technican told me that he had changed heat sensor and according to his explain maybe the new sensor was defective. According to his advice; after unplugging I have to make a short circuit on that plug using a piece of wire.
1. What is your opinion about working cooling fan problem?
2. Do you think technician's guess is correct?

Lastly, since I am a novice on Porsche, sorry my using wrong/or mismatched word.

Regards,

Flying Finn

First, one question: Does it run "forever" or just for 5-15 minutes?

1. If not "forever", that is normal.
2. If not "forever", your next question is: "where to find good Porsche mechanic in my area?"

Robin 993DX

The heat sensor located on the left side heater duct may be defective, if it is defective it will cause the engine bay cooling fan to stay on.

The below picture shows a partial picture of the sensor where the screw driver is pointed at.

Tom Pepper

Did your new purchase of the 95 993 include the updated wiring harness? If not, all electrical gremlins should be attributed to the harness untill proven otherwise.

ataman

1. The problem occurs eventhough I don't drive.. The fun works whenever I turn ignition on and it doesn't stop unless I unplugged fun motor's power.
2. I found an air temperature sensor from pelicanparts.com. Part number is 96465912000. Is this the part needed to replace?
3. Robin; I could not find the sensor which you were trying show me with the picture.

Many thanks.

Flying Finn

If it's always on, as Robin said, you probably have bad sensor.

If your car is early -95, it can have heating system similar to 964 and that's why you can't find it.

Does you engine bay look different than this (the heater area)?

Robin 993DX

The temp sensor's location like Finn said is different from a 95 and 96, the picture taken is from a 96 993

The part number is 964 659 120 00

ataman

Dear Finn;
My car's motor is the same with yours.
Dear Robin;
Thank you for your part's number confirmation. I have already ordered it. As soon as I get it, I will let you know whether I solve my problem or not.

csertich

As stated by Mr. Pepper, make sure you check into your wiring harness-if it's the original that came on the car, it should be replaced (by Porsche at no cost).

Good luck and enjoy your car.
chuck

ataman

Even though I bought & replaced "The temp sensor", part number is 964 659 120 00; I have still the same problem.
What do you suggest me? Do you think the cause is due to fan relay? If yes, where does it locate?

Ataman
'95 993 C2

PK

Ataman,
Pardon me for not quite understanding the problem you're describing...

Have you tried to turn the temperature **** on the climate control unit all the way to cold ( below the 18 degree C mark ) and turn the ignition to on ( without actually starting the car)? ...and see if this would stop the fan?

Just trying to help...

ataman

PK,

Yes I did what you said me and it worked. The fan stopped. What is the explanation?

Many thanks

ataman

Here is my follow up information - what I did in order to solve the problem:
1. I replaced temperature sensor with the new one- it did NOT solve the problem.
2. I checked fan relay- when I removed relay, fan stoped. But when I replace another relay, the same part #, the fan still works. Obviously the relay is intact.
3. Last monts, I changed my A/c Control Unit (CCU), #99365904701CJH. It was original & brand new, I bought it from vertexauto.com. Whenever I pull out A/C Control Unit's fuse, the fan stops.
Somehow, CCU interferes the cooling fan working condition. Even though the ignition is off position, the CCU will send impulse to the fan. Weird. Supposed CCU is to be dependent to ignition on position?
Any comments?
Thanks...

Adrian

Dear Ataman,
The 1994 and 1995 993 air con and heating system is basically the same as the 964 system.
The rear blower fan has two functions. One is to blow cool air into the heat exchangers and this air is then heated and pushed forward through two differential pressure flapper valves to the heating system. This system requires the rear blower fan to run as soon as the ignition is turned on and the temp control **** is out of the blue dot position. The fan will not run when the temp control **** is in the blue dot position.
The second function is additional engine cooling. This can occur with engine on or off. With engine on and when the temperature in the pipe behind the blower (as measured by the NTC temp sensor) reaches above 75C the fan will crank up to high speed.
When you shut the engine off and the air temp in this pipe is less than 30C the aircon and heating control unit switches off. If the temp is 30C or higher the aircon and heating control unit will remain active for 15-20 mins. If the temperature in the pipe reaches 75C the rear blower fan will be activated at low speed until the temperature drops to 70C. This may continue until the time limit is reached. This system protects against heat soak.
If you disconnect the NTC temp sensor this system is disabled.

So knowing the basic theory we have to look at the cause. We know it is not the temp sensor because it has been replaced. We know it is not relay because it has been replaced. Therefore the only thing left is the control unit. Now we have a small problem here. I have no idea where you live and what version you have. The other problem I have is the part number of the control unit which you replaced. I can tell by the ccu part number you have posted that you have a LHD 993. I suggest that you need to check the original number because I have a feeling it is a 00 and not a 01.

What I would ask is for you to do the following.
1/. Before applying power to the 993 turn the temp control **** to the blue dot position and check the rear blower fan is not running.
2/. With the engine running turn the temp **** to the red dot position and ensure the fan starts running at low speed.
3/. With engine running turn the temp **** back to the blue dot position and make sure the rear blower fan truns off. This may take some time.
4/. Turn the temp control **** to 27. The rear blower fan should start running. The select the blower speed to 1 through 4 and make the fans run at the selected speed. Then turn fans off.
5/. Turn the temp control **** back to the blue dot position. Make sure rear blower fan turns off.
6/. Select defrost. Make sure the rear blower fan cranks up, the aircon may also engage, make sure the fans up the front crank up to maximum speed and make sure hot air is blowing out of the side vents and the windshield vents.
7/. Go for a drive. At least 15 minutes. Take a pen and paper with you. Keep the temp control **** at the 27 position or around this area. When you get home let the engine idle and record the engine temperature pointer position. Turn engine off. Does the rear blower fan keep running?
If it doesn't, sit behind your car for 20 mins and see if the fan cranks up at all. If the fan does crank up immediately turn the ignition on and record the engine temp pointer position.

This should keep you busy. Please also tell me about your 993. Is it a real 1995 model or an option M718 1995 model which is really a 1994 model and requires the earlier ccu.
This can be found on the options label which is on the underside of the luggage compartment lid.
Ciao,
Adrian
964C4

Randall G.

Hey Ataman,

I'm looking closely at what you've written in number 1 above. I'm also looking at your response to PK (fan shut off when taken to blue dot).

-With the ignition on, and "heat requested," it's normal for the rear blower to operate. Heat requested typically means the temperature control **** is set to something like 21C or greater, but will vary with ambient temperature.
-As Adrian writes above, the rear blower is running to provide heated air to the cabin.
-When you took the temperature control **** to blue dot (ignition on), there was no request for heat, the fan shut off. As it should, if the engine isn't hot.
-If the engine is hot, ignition on, and the temperature control **** is at "blue dot," the rear blower will operate as an engine cooling fan (as Adrian as already written).
-If the ignition is off, the rear blower will operate as an engine cooling fan. It may run for awhile after the engine and ignition are turned off, until the engine cools.

Sooo...to clear things up, is your fan running with the ignition on, engine off, temperature control **** off of blue dot? If this is your problem, well....you don't have a problem.

Is your fan running with the ignition off (e.g., key completely removed), with the engine completely cold? Does it continue to run indefinitely (to the point where it will drain your battery)? If so, you do have a problem.

Hope this helps!