I had jumped in earlier in this thread, and after reading the feedback, I carefully monitored my 45 minute commute yesterday afternoon. The temp was 98, the car had been in the sun but the tinted windows were cracked and I had a "solarshade" in the windshield. Once I started up, I opened all the windows, set the A/C to 72, let the A/C come on for a minutes before closing the windows, and started my drive. I did not have it on max A/C, and for five minutes I had a nice flow of cold air. However, for some reason the sensor is telling the A/C to back down on the cooling well before the vehicle interior is at 72. I have to bump the control down to 65 for twenty minutes to get the interior cool enough where I'm not sweating. During the last part of my commute I gradually bump the temp up to 70, and I did note the short period of warm airflow that some folks described.
Like I said earlier, I can live with it, but it sure does have me puzzled. It's almost like a "fuel economy thing", where sensors try to keep the compressor from working hard and impacting gas mileage. Okay, that sounded stupid, I'll shut up now.

 

Just my 2c here: normal airflow, dash vent on. No problems keeping the car cool. Indeed, my girlfriend often turns her fan off since she gets colder. I leave it on 69-72 depending on whether I feel cool or warm and let auto do its business. Eventually, I back it off to 1-2 bars. I do have the panoramic roof. Very pleased with the system, especially coming from my 2000 911 cab (which also was more than adequate). Maybe I just like it a tough warmer in the cabin?

 

I have an update on the weak A/C issue. I took my wife's 2011 Cayenne S to the dealer about ten days ago and complained of the problem I described in my earlier post in this thread:

"We are also not liking the performance of the AC on my wife's 2011 Cayenne S. When the vehicle first starts up, the AC blows cold air but very quickly (and prematurely) dials back unless we lower the temperature setting to 65 or lower."

The dealer checked the refrigerant level and found that it was 50 grams low (out of 850 or so fully charged), so he filled it to spec level. Unfortunately, the same symptoms remained. I finally got a chance to take the vehicle back this afternoon, and my service advisor decided to call a Porsche technical support engineer. He told my service advisor that Porsche is aware there is an issue, with multiple complaints coming in especially from the southern part of the U.S. It turns out that Porsche is using an infrared cabin temperature sensor that is located at the lower right corner of the trim surrounding the instrument cluster. It is a quarter-imch or less in diameter and looks like the red plastic on the transmitting end of a remote control.

The problem arises when the air blowing out of the A/C vent just to the right of the instrument cluster is set for unrestricted flow and is pointed directly at the driver. The sensor registers the effects of the cold air on what the sensor is "seeing", which is the back side of the steering wheel and the driver's shirt or blouse. If the shirt or blouse is made of a loose fitting material and/or light colored, the sensor "sees" the temperature of that material (which cools more quickly than the rest of the interior) and prematurely dials the output air back since the sensor thinks the desired setpoint has been reached.

The likely permanent fix is going to be to relocate the infrared sensor somewhere else in the cabin so that it registers something more representative of the overall cabin temperature. The short term workaround is to dial back the output volume of the A/C vent that is just to the right of the instrument cluster and to aim it just to the passenger side of center of the vehicle.

I know this seems somewhat strange, but we tried it on our way home from the dealership with an outside temperature of 98 degrees F, and we were very comfortable with a temperature setting of 72 degrees F.

 

Thanks for the information and workaround . . . I'll give it a try.

 

@jfr, it's interesting that you mention this observation. Perhaps the reason that I have been satisfied with my AC is that I always keep the center dash vents centered and pointing/aimed up.

 

That is consistent with what the Porsche Technical Support Engineer says is going on. I'm just glad I went back to the dealer the second time to complain and that the service advisor finally decided to call the technical support engineer. It was actually pretty funny - the service advisor started to tell the engineer what problem I was having, and the engineer stopped him after only a few words, and proceeded to describe exactly how our A/C had been acting and what was causing it.

 

As I'm sure that there are many components that are shared with the Panamera, I wonder if they have had issues with their sensory systems?

Have you tried posting on the Panamera list?

 

I took a look at the Panamera owner's manual PDF, and it looks like it uses the same type of sensor. I'll check the Panamera forums out to see if there are any A/C complaints there.

 

Well, it just so happens that when I took my 911 Turbo S in today for the Center Lock hub recall, I was given a Panamera loaner. The infrared sensor for the A/C is located in a somewhat similar spot to that of the Cayenne, but it is not as directly in the path of the air coming out of the left center dash vent as the one on the Cayenne is.

The A/C on my loaner Panamera functioned perfectly well on my trip home from the dealer, despite me intentionally pointing the vent directly at me. This leads me to believe that relocating the Cayenne's sensor should be the permanent fix for its problem.

Meanwhile, my wife is continuing to use the workaround positioning I described in my previous post, and the A/C is functioning well on her Cayenne S.

 

Thank you for the clarification about Dubai. Makes sense. It's right on a body of water. I rarely try to second guess Porsche. They have some of the best engineers in the world! As someone with a physics background and living in Texas I can say without a doubt humidity is the largest single factor by a very significant margin in effective airconditioning. Certainly the very hot temperatures of Dubai coupled with the very high humidity make a perfect testing environment for automobile airconditioning. Very few automakers seem seem to understand this. Especially outside the US. Good that Porsche does. Mercedes does, BMW for the most part does. Porsche has one additional advantage. They seem to have figured out that the dashboard gets very hot due to solar radiation alone. The resultant infrared emanating from the dash reflects off the windshield (since very low frequency IR does not penetrate glass/plastic composites well) and falls directly on the occupant's faces. This is a very uncomfortable situation in any hot, high solar radiation environment. Therefore, cooling the dash and the occupants faces (at least to some degree) should greatly increase comfort. Porsche is the last remaining automaker, as far as I know, that has upper dash vents. (BMW had them on the previous generation 3 Series, but no more). Bravo Porsche for being so astute on air-conditioning. Those of use in very hot climates are extremely grateful

 

We have 4-zone climate control on both our Panamera 4 and Cayenne S, and we don't have any issues with the AC. With the 4-zone, you get a secondary AC unit and additional air vents on the B-pillar, even when you do not carry rear passenger routinely, it will still cool down the car much faster, especially when we have panorama roof on the Cayenne. We were going to buy the Cayenne Diesel and since 4-zone climate control is not available on the diesel, we bought the Cayenne S instead.

 

An update - it turns out the cause of the "weak AC" performance on our 2011 Cayenne S was due to (believe it or not) cold air blowing onto the back of the infrared sensor through the slits where the air vent to the left of the PCM attaches into the dash. Here is the Porsche fix:

 

Don't see anything?

 

I attached a PDF in my previous post. When I click on it, it goes to my download folder. Let me know if that doesn't work for you.

Also, your dealer should have access to the bulletin.

 

Mine is in India and cools very well even when standing out in the sun, its a 2006 V6. We get temperatures upto 45Deg C and service intervals are down to 10,000 kms.....