A/C pressures and fan speeds.

[wrinkledpants]

My 04 CTT's AC just hasn't ever seemed that cold.  Had it recharged today at the Porsche dealer.  They said it was down .5 lbs, but I don't feel any difference in the temps.  I took a thermometer out and measured the vent temps.

 

Test 1:Ambient 70 degrees, Parking garage (no sun).  HVAC (4-zone) set to Low.  Waited about 5 minutes, and the center vent temp was at 52 degrees.  All the front vent temps were about the same.  Went to my wife's 04 A4 1.8T with 150K on the clock, and the vent temp was 42, and felt more appropriate.  

 

Test 2: Ambient 75 degrees, interior 95 degrees.  Set to Low, and temps came down to 70 degrees in about 2 minutes.  After 7 minutes, the temps were at 60 degrees and holding steady.  

Test 3: started driving from Test 2, and through city streets, vent temps went down to about 40 degrees with the HVAC on Low.  Once I stop, the vent temps start to climb.  Rear vents are a bit warmer than the front.  

 

According to the porsche after sales docs, the engine fans should kick on at full speed once the PSI in the high pressure side hits 250 PSI.  I've never seen my engine fans go to high speed on the CTT.  On previous VAG cars, high speed engine fans sound like vacuum cleaners.  Mine are spinning, and only audible if I put my face near the front bumper.  

 

If it's hot out, and I've selected max AC with a fully recharged system, shouldn't the high pressure side PSI increase enough to kick the engine fans on to high speed?  It's possible my flap motors might be bad, but there are 4 AFAIK on this car.  And, it's hard to imagine they all failed in the same way so that the temperate at the vents is all the same.  Either that, or there is something wrong in the AC system preventing the car from generating higher pressures?  

 

Any other ideas?  I'd think a car with this capability and 2 AC systems would be able to make cooler air than my wife's A4.

[bigbuzuki]

Run the test as per the attachment.

Aircon ops test.pdf

[wrinkledpants]

Wow - according to that document, the 2-zone is the better AC setup.  It can maintain cold vent temps at a higher ambient temp, and it's high pressure values will hit the 290 PSI mark, triggering high speed fans at a low ambient temp.  

 

I thought the 4-zone would have been the meet locker champ, but it's the 2-zone.