Poorly Informed PCNA Rep.

[wwest]

I have a letter right here in hand dated September 11th, 2004 from Rick Podorski, Western Regional Service Manager for PCNA, Porsche Cars North America.

It is in response to my enquiry of September 1, 2004 regarding the status of a firmware update fix for the climate control system in my 2001 Porsche C4. The C4's climate control system often ("part of the system's normal operation." R. Podorski) cools the windshield so severely on a hot and humid day, or night, that the exterior surface of the windshield will fog over, sometimes almost instantaneously.

I had noticed on a web forum that the VW had issued a firmware update for the Touareg SUV that corrected this very problem. So basically my question was if VW has fixed the touareg climate control then the VW fix will probably be applicable to the Cayenne and maybe my C4.

Here is a single sentence from my letter which will indicate just how well we can expect a factory service representative to keep up on these things.

"Porsche Cars can appreciate the time you have spent researching this matter with another manufacturer, but these are two different systems that cannot be compared."

The VW Touareg and the Porsche Cayenne climate control systems CANNOT BE COMPARED!

Hmmm...

Maybe someone should inform the workers and/or the buyers in the jointly owned Porsche/VW factory where both are build using 90% of the same components.

Just as asian manufacturers primarily use NipponDenso, many european manufacturers use Bosch as a resource for electrical and electronic designs. I verified just last evening that an owner of a new BMW has exactly the same complaint. His solution is to lay a towel over the windshield airflow outlet ducts in the summertime to prevent the windshield outside temperature from declining to dewpoint.

[mudman2]

Its purely a function of the temp setting, none issue. set it to 73 on a hot day and it does not happen.

[wwest]

Sure...!

[mudman2]

Hey you asked, just because you don't like the answer does not make it incorrect.

MB and most other ac cars have this problem, actually Boeing 707s also had it. If you set the temp too low the laws of physics take over. Its not magic.

[wwest]

No, not magic.

And yes, you're right.

If I have the setpoint at 71 and the system is cooling the windshield I can reset it to 73 and it will not not.

Until the passneger cabin air temperature rises to the new setpoint.

The windshield heating system in the 707, and many other Boeing jetliners, track the outside temperature and raise the windshield heating level accordingly. Most common failure is actually windshield cracking due to overheating.

I know of absolutely no circumsatnce wherein it would be appropriate to CHILL an interior windshield surface.

Only God knows why but in a Lexus you can actually activate the defrost/defog/demist mode with the system blowing COLD air to it. Most manufacturers have the good sense to HEAT the airflow to the windshield in that mode.

Lexus does have a CAUTION note in the manual advising that the defrost/defog/demist mode should not be used to CHILL the windshield when the weather is hot and humid.