Tom Pepper

While replacing my wiring harness AGAIN...the replacement which I had done last year was also the dreaded .05 part number...I had the dealer repair my non-functioning defrost.
I was told I had bad fresh air and defrost fan motors...700 bucks! Guess what! This resulted in an incomplete fix,"but you needed those motors replaced". The "resistance" apparently blew the climate control unit which I now also need...1,500 bucks. So far I have a $2,200 tab for a defroster fix.
Any thoughts or experience with blown motors and CCU replacement to fix a defrost malfuntion? I am getting that feeling that the dealer is playing proctologist again.


<img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Randall G.

Hi Tom,

Sounds fishy to me .... seems unlikely that you would have two (!) motors and the CCU failing at the same time. Perhaps an incorrect diagnosis with excuse?

When you write "fresh air and defrost motors," are you speaking of the servos or the interior fans (on the left and right side of the luggage compartment)?

Have you already purchased the CCU? Don't pay list! You can save hundreds of $$ at a discount dealer, such as Sunset Porsche.

I think you can troubleshoot this system yourself, given the information contained in the previously linked 964 threads. At a minimum, you can certainly check servo operation.

Best of luck!

Mike Lincoln

Well, a frozen motor would draw much more current than normal. For instance, when a regular, mechanical motor such as a fan or compressor motor begins to seize, it heats up dramatically due to the increased draw. I can imagine something like that doing electrical damage to a (hellishly expensive) attached part like the control unit.

Sorry, Mike

Mike Lincoln

Hey, just doing some late night browsing, and I found a climate control unit for $350 exchange at: <a href="http://www.911pcar.com/porsche_parts_electrical_993.htm" target="_blank">http://www.911pcar.com/porsche_parts_electrical_993.htm</a>

Not sure if its exactly what you need, of course...but maybe worth examining.

Mike

Tom Pepper

I appreciate the thoughts and the research. They are already into the repair, so I probably missed the chance to DIY.
I will post the final tally and let you know what those motors looked like...they better be frozen.
Thanks <img src="graemlins/wave.gif" border="0" alt="[byebye]" />

Craig W.

Hhmm, make sure you get the motors back, and tell them *now* because you can bet they will conveniently lose them. And make sure to tell then that if they do lose them, you will not be paying for the repair.

Sure sounds like a misdiagnosis to me, something you should not pay for IMO.

Randall G.

Hi Tom,

A few more thoughts ...

-If the motors being replaced are for the left/right interior/defrost fans, they're fuse protected. So, one of these fan motors seizing would simply blow the fuse. Actually, for these fans, the power doesn't come from the CCU, it comes from Term 30 (always "hot" 12V). Also, you would only replace one of these fans--it's not likely for both to be seized at the same time.

-I'm guessing that the dealer replaced the servos for the fresh air and defrost flaps. The servos receive 12V and 5V power from the CCU.

-The 12V is used to power the servo's motor. If the motor shorted or seized, I suppose it could damage the CCU (don't know enough about the CCU to say otherwise). The 12V power for each servo motor is unique. However .... people are replacing non-functioning (seized?) servos all the time, without replacing the CCU.

-The 5V is the reference voltage for the potentiometer that's used to tell the CCU what position the servo is at. However .... the 5V is common to all servos, so if the 5V supply is fried for one servo, none of the (5) servos would work.

So, I can't say with certainty that the dealer initially misdiagnosed your problem (though I'm guessing they did), and that your CCU wasn't fried by a shorted or seized motor. I also can't figure out what the fresh air flap servo motor has to do with your defrost function. I can only surmise that they found another problem while diagnosing your in-op defroster fan.

Pulling the thread just a little further. The fresh air and defrost flap servos don't share any power/signals that aren't common to other servos (which I understand are working fine). So ... if what the dealer is telling you is true, then you had two failures:

1) A seized (or shorted) defrost servo motor, which in turn fried the CCU's defrost circuitry.

2) A second servo (fresh air flap) that just happened to have died about the same time.

Hope this helps, and good luck!

Tom Pepper

Thanks Craig and Randall.
This is uncharted territory to me. The likelihood of the dealer making a diagnoistic error then dancing around it looms large.
Should have some answers this week. I really do not want to have to pay big and unnecessary bucks for thier misdiagnosis. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

E. J. - 993 Alumni

Hey Tom, hate to throw salt in your wounds, but my service manager did about 3 weeks of research with PCNA and the DSMs on the East Coast and found that the part number ending in .05 is only half the check they should perform on the harness. Seems any build date on the harness later than Jan 1996 will not require a new harness. I think this is where the cut off for the 1996 cars came from. My previously replaced harness also ends in .05, but has a 2000 build date, so I am not going to have to replace a perfectly good harness and will be able to go after the reimbursement.

I will say at the dealers defense that the only reason he found this out was because I pushed him for an answer. I knew enough of the problem to know that the harness I used 2 years ago would be fine and I forced him to work the phone. If you need a refrence, it was Chad (Service Manager) at Porsche of Arlington, you can find their website pretty easily. Might want to call him to find out who specifically he got this information from at PCNA. Maybe you could still go after a reimbursement to help offset the other BS charges they are clipping you for.

Good luck,

E. J.

jhb

I have a hard time believing a siezed motor would blow the CCU. A siezed motor does pull more current but no more current then the "initial" draw at motor startup, which the power supply should handle without blowing.

Randall G.

Not that I believe what the dealer is telling Tom in this case, but .... Using a P-car example, binding/seized rear blowers are notorious for blowing the fuse. So, the binding is causing a draw much higher than normal or even start-up. Then again, drawing enough current to blow a fuse and destroy a circuit is not quite apples to apples. And, as I wrote before, lots of people replace nonfunctional (likely seized, but unverified by myself) servos without replacing the CCU.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />