Oil Cooler Fan Question
 

I know this topic has been discussed at length but being technically incompetent, and not knowing how to perform the wiring bypass test, here's my question:

When my car is stationary and oil temp reaches 9:30 level, the oil cooler fan comes on (i think it's on high because it feels the same as the a/c blower) for about 10secs, and then goes off completely. Fan comes on again after 5mins for 10secs and off. This 10sec on, 5min off cycle repeats itself when oil temp level is at 9:30. I can never seem to feel the slow speed fan.

When my mechanic plugs the Bosch hammer tool into the centre console, it shows no fault or errors.

So is my oil cooler resistor faulty or not? If it is, shouldn't the fault show up on the Bosch hammer?

I'm not an expert, but I doubt a faulty fan resistor will show up on a hammer. It's probably just a temperature triggered circuit. When the temp gets high, the fans goes on. When it gets low, the fan goes off.

Follow the procedures for diagnosing your high speed fan and then install the oil cooler fan switch. Or even better, install a turbo s oil cooler or cargraphics oil cooler.

My oil cooler fan would not come on at all.
I pulled the relay and did the relay bypass p-car test and the fan would not come on at all slow speed or fast speed.
The dealer said the resister is the most common part they replace so I tried it.
When I pulled the old one out it was in three pieces.
I replaced it and tried the relay test again and sure enough I could manually get the fan to run in slow and fast speed.
Now as soon as the temp gauge shows 9pm the fan kicks on and stays on until the temp drops.

Steve

I got two of the switches at Hershey this past Sat. for a total of $11. Now I have a spare! DIY install will probably be before my May 22nd DE and I'll post a full report.

993C4,

1) The A/C fan runs continuously on low speed anytime the A/C is on. The "breeze" you're feeling from the A/C fan is the fan's low speed.

2) The oil cooler fan turns on to low speed at about the 9:30 position that you speak of. That is normal. It is also normal for the oil cooler fan to cycle on and off like you describe.

It looks like your oil cooler system is functioning normally. You may, as a precaution, want to change the oil cooler and A/C fan relays and ballast resistors sometime. They are high mortality parts.

Re: Oil Cooler Fan Question
 

Don't underestimate your abilities. Check on Robin's site (p-car.com) for the wiring plug behind the right headlight to disconnect to test the cooler blower. This test is easy for anyone to do.

I had the same fan cycling as you did. When I disconnected the plug, the fan went on high speed. It turned out that my resistor was bad. I had both resistors replaced while the bumper cover was off just for insurance. The new part is a lot more durable looking than the old one.

BTW, I also now have an override fan switch - highly recommended of you autocross or track your car, as it makes a substantial difference in the oil temps. Directions on Robin's site also.

Rick,

Please be sure to post your oil temp experiences as I'm also trying to figure out how to control the operating temps around here.

Thanks

Skip

Skip, I might get to it this Sat., if the lady lets me out of the house. I have to use up some of my car credits with her to go to the Deutsche Marque concourse show in Sunday. I also want to install my RS heater bypass tube this weekend, since cold weather is leaving us. Hell, I may just drive to the Metro parking garage to do it in seclusion;).

Re: Re: Oil Cooler Fan Question
 

I'd go as far as recommending this for anyone who commutes with their 993 and/or lives in a warm climate. The switch is a highly effective, cheap, and easy (how often do you get all three of those together) method of controlling your oil temp. which, in turn, increases engine/component longevity. Food for thought :)

Edward

Rick and others,

I actually went ahead and did the oil cooler fan override switch tonight. It took about 1.5 hours and I am slow (keeping with my HWFMR team membership) with this stuff - it wasn't hard at all, just a little time consuming.

I have the 944 switch on order for the center console, so I just used a cheap Radio Shack flip switch for the time being. Once the switch is turned on, the fan takes about 15-30 seconds to actually start, but will turn off in just 5 seconds or so.

I'll report back soon, when I have had to sit in traffic and the heat.

-Skip

Interesting. I am under the impression that my fan starts and stops immediately when I throw the switch. I'll have to check that.

I used a second fog light switch from Gert in the blank spot on the dash. Now if I could get it to illuminate when it is in override mode, it would be almost perfect: Normal position is pulled out, pushed in to turn on the cooler fan.

993C4,

I agree with Pete, sounds to me like your resistor is toast, and you're getting momentary cycling of the fan in fast-speed. If the slow-speed fan is operable, it will run for several minutes, and you can actually see the oil temperature drop below 9:00 before it turns off. If your fan isn't running long enough to actually cool the oil, something is amiss.

This momentary cycling is similar to what people see when the A/C condenser fan ballast resistor fails, and the fan cycles in fast-speed, as the slow-speed fan isn't running continuously like it should.

You won't have high confidence the resistor is bad (or good) until you perform the jumper test.

I do believe the Bosch Hammer is supposed to be able to identify a faulty resistor. I don't have my shop manual here with me, but--if nothing else--I'm pretty sure the hammer can be used to turn the fan on and off. If someone has their shop manual handy, they should be able to find what the hammer can/cannot do in the trouble-shooting section.

Pete....Yup, there may be a delay, after flicking your switch, before the fan starts running in fast-speed. I think it takes a short while for the CCU to recognize that there's an open circuit, then switch into its default mode (fast-speed).

Skip, you've inspired me. Mine is going in on Sat.

Rick,

Which switch are you going to use (rear fog lights, 944 hazards, or radio shack special)?

I'm going to use the 944 hazard switch for the center console. Since I know the setup works and I have a radio shack $1 switch working, when the 944 switch comes, I'm going to see if I can figure out a way to replace the triangle with a fan symbol. That should be fun to figure out and make the install really look OEM.

The directions on Robin's site are perfect and exact with regard to which wire to cut from the back of the CCU and everything. It worked just as documented.

Good luck,

-Skip

This may be a stupid question, but why install a switch? If the resistors are working properly, shouldn't it keep the oil at the correct operating temperature?:confused: