Fugg this cooling problem.

[PorscheG96]

I finally found the cooling fan resistors thanks to Chris luckett and Gabe's 951 with the engine removed. I tested the resistors and unfortunately got the proper resistance. What I proceded to do was unplug each resistor one at a time and see if there was any difference in the operation of the cooling fans. What I noticed is that when either resistor is unplugged the initial cooling still doesn't come on, but when the primary cooling activates at the third white bar on the temp gauge the fans cycle back and forth between low and high power about every 10 seconds. I'm not sure what this means, just an observation...can anyone make sense of this and does it sound right? This is the first time I've even witnessed my high power fans coming on the entire time I've owned the car, otherwise I only get the primary fans at low power. Any other things that I can look at, I'm going insane here.

[Mrmerlin]

Hi It sounds like a fan relay is bad

[PorscheG96]

New fan switch on radiator, new fan relay, coolant bled, new cap for expansion tank to hold pressure, and resistors check out...still no initial fan at 9 o'clock on temp gauge. I guess there's one more thermoswitch somewhere in the system that I can check, but I'll have to find it first...

[todwic]

Change temp sensor that's right under the throttle body and make sure connection is cleaned/new. My fans kick on a little past the middle bar and stay on untill white line. (barely operating temp.) I put a bottle of water pump lubricant and some Waterwetter in it and haven't gotten even close to as hot as you are getting. Change thermostats, too, to the lower temp. Mine had the old stock one in and the current one opens sooner and wider. As for the cycling, go to the PCA website, the tech section and the 944 guys has a tech Q/A that covers this. He explains it, tho not quite to my satisfaction.
http://www.pca.org/tech/tech_qa_area.asp?id=10
http://www.geocities.com/MotorCity/Flats/7407/

[Z-man]

Originally posted by todwic
As for the cycling, go to the PCA website, the tech section and the 944 guys has a tech Q/A that covers this. He explains it, tho not quite to my satisfaction.

My mechanic doesn't buy into the "Working properly" explanation either. I've got the same 10-second cycle occurring on my 944S2. New fan switches, new thermo, new expansion tank cap, coolant flush (no air), and my mechanics have already spent some quality time with my baby trying to figure out this cycling. It's going back on June 3rd for more research and hopefully an answer.

PorscheG96: I feel your pain!

BTW: Did you guys know that our engines (at least the 944S2) have coolant running through the throttle body? This is to prevent a condition known as icing: when moisture in the throttle body freezes in the winter, causing the throttle not to work properly. You can easily bypass this by connecting the two hoses going in & out of the throttle body together: that way you have a little colder air feeding the engine: probably good for 0.006 horsepower! (At least that eliminates one sensor in the system!)
I can post pics of the throttle-body coolant bypass in anyone's interested...

-Zoltan.

[PorscheG96]

Zoltan, do your fans just cycle between high and low power under normal conditions [ie. when the car gets warm] or only when the AC is on or what? Your problem is just one of the fan resistors. I only got cycling when I REMOVED one of those resistors, so it wasn't doing it's job. My problem is with the initial cooling not coming on...no fans until third white bar.

[todwic]

when I say whiteline (barely op. temp.) I mean the first solid white line. In my worthless opinion, I think your thermostat isn't opening up all the way, thereby keeping the hottest water at the temp sensor, and not letting it cerculate(bah!sp.) to the fan switch thermo probe, if that's possible/makes sense. The other thermo probe is looking sumpin like this
I changed all the parts I mentioned and put the luby stuff in and now I can keep my bra on and she still doesn't get too bent out of shape when I go up the "Grapevine" (a rather largish hill in California). She used to scream "I'm too G.D. HOOOOT!" 1/4 of the way up.

Good luck with that, Z-man and if you figure it out, give us a post, eh?

[PorscheG96]

It's not the thermostat, that's new also...it was changed with my belts/rollers/waterpump 15k ago. When I short terminals 2 and 3 on the plug going to the thermoswitch I get both fans coming on at low power, but when I short 1 and 3 nothing happens...I should have another fan coming on at that point. It's definitely something with the electronics, but I think I've solved Zoltan's mystery by testing all these things in my car, notably the resistors.

[Z-man]

Originally posted by PorscheG96
...but I think I've solved Zoltan's mystery by testing all these things in my car, notably the resistors.

I'll give my mechanics a copy of this post: maybe they'll give you some of the $$ I give them to solve this problem!!

I do know they have removed/bypassed many of the temp sensors throughout the system to try to narrow down the
problem, but no matter what they did, the fans would still cycle.

My cycling problem occurs when:
1. I turn on the AC (to activate the second, high speed fan)
2. When my temp gauge reaches the first white bar (9 o'clock position).

So, I'll keep you guys posted after June 3rd!
-Z.

[PorscheG96]

Here's where the resistors are in case you don't know...they moved them for cars w/ dual airbags. If you could ask them where the second thermoswitch is located while you're in there, that'd be great [you'll see there's a blank mounting hole on the right side of the bracket holding the resisitors, this is where the other thermoswitch is mounted for cars without dual airbags].

http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=15&t=007050

[gforces944]

Make sure that your radiator isn't clogged either...If you've ever blown a head gasket or had a condition where oil might have mixed with coolant, your radiator might have been affected and be working only at partial efficiency.

It's difficult to tell since the radiator cap isn't directly on the radiator. Once, I was constantly overheating after replacing the oil cooler seal, and there was no residue whatsoever on the rad cap. Dropping the radiator and taking it to a radiator shop revealed that there was a slimy sludge coating the interior of my radiator, and the guy said I was at only 20% efficiency...they cleaned it out and I was coolin again...

just something to think about.

[PorscheG96]

My 968 has never had the oil and water mix [from oil cooler seals or head gasket] and I've tried to make it clear that the fan isn't coming on. The car doesn't run hot...it cools right down once the fan comes on but I'm not getting the early fan.

[Z-man]

Originally posted by PorscheG96
Zoltan...Your problem is just one of the fan resistors...

Update: Yep: That's what it was! My mechanic finally found a short in the resistor, and was able to solve the problem!

Good call!
-Zoltan.