Cmdykstra

Something strange that has plagued my 1996 993 for quite sometime. When I turn the fan on the CCU to '3' (sometimes on 2) the power to my dash starts to dip? This last time it happened it put my car into 'limp mode'. I was able to reset the ECU and it came back to normal. It's like there is a short somewhere but I'm not even sure how to start looking. My mechanic has never been able to isolate this. Like it's never happened when he has it (something I find a bit hard to believe) Just looking for suggestions. Other than this the thing runs like a dream. Maybe related...the radio will occasional turn on and off....but not all the time? Several years it's done this but never gotten worse.

pp000830

Hi Cmdy,
Please describe what you mean by "the power to my dash starts to dip?"
Andy

ToreB

When the two front blower motors wear out, the sintered bronze motor bearings may pinch the axle and cause excessive current consumption. The problem varies depending on the fan motor temperature.
This might cause the problem you describe. You can remove the pollen filter covers and try to rotate the fans. If they do not rotate freely they must be changed.
Cheers,
Tore

Cmdykstra

Yes, sorry my description wasn't the best. So at night if the headlights are on they will dim, down and come back up. Also the backing lights of the dashboard gauges. The electronic read out in the gauge w/ temp/speed/fuel etc will also dim in and out. And the radio will shut off, then turn back on. Typically, then I will change the fan selection to 4 or down to 1 or nothing and then the issue goes away. It so sporadic though. It won't always do it. It's strange right? It will do it with the air conditioner on or off.

Cmdykstra

I will look at this. Thank you so much for the reply and your thoughts!

VladiD

I am experiencing a similar thing in my car. When I turn the headlights on, the CCU will suddenly go on full blast, no matter what the temp/fan setting is at. I will need to get that looked at eventually.

pp000830

Check the connections to the batter and the alternator.

Cmdykstra

Hello, I wanted to close this out so in case anyone else ever has this issue....no need for them to suffer.. There ended up being a short of some kind in the CCU unit that was drawing extra power and causing the weird issues. I had it rebuilt and upgraded by Specialized ECU Repair and all the issues have all gone away.....thank freaking god.

systemsc

Please define what "upgraded" means? The CCU is very reliable and rarely fails. The CCU itself is incapable of causing, "the power to my dash starts to dip". Most likely you have a bad blower as ToreB indicated.
Your "rebuild" has modified something in the CCU that masks the actual problem, that most likely still exists and will re-occur.

systemsc

Sounds like you too have a 12V system supply problem unrelated to the CCU.

Cmdykstra

I would point you to Specialized ECU Repair for their explanation on all they do to the CCU. All I can say is the issue are now resolved. I guess when I first posted this last year your input would have been helpful, but since you didn't and now my issues are resolved. I say Thank you and good night.

Cmdykstra

I would have to ask then would this be something detectable under testing and diagnostics and my Porsche mechanic? The testing they did led them in CCU direction, I got it rebuilt, issues resolved. Not sure I'm going to dig anymore for a problem that no longer exists. I was only tryin to assist anyone else who ever has anything that looks like this. Literally NO ONE had any ideas that helped really and the mechanic that did end up finding the problem looked at me like I was crazy when I was explaining it.

systemsc

Yes, if he fully understood how the CCU really functions.

Indirectly! As an example, if the actual problem were the inside blower motors, the problem would only occur when the CCU was functioning.
Thus, someone could possibly conclude it was a bad CCU.

Who knows what they really did to potentially mask the real problem? In reality, there's no way the CCU can directly consume enough power to affect what was happening.

Cmdykstra

Holy Sh*t man, as if my piece of crap car heard you......it started doing again. I'm at an utter loss for words at this point.

Cmdykstra

I guess I'll have them go after the blower motors now. When it goes haywire, there is a kind of clicking sound from the fan. It's definetly weird though. Acted up on the drive to work this morning (2&3 settings), fine the rest of the day...damn thing.