AFAIK- there is a single evaporator coil on the front only systems - so how does a low charge change the temperatures side to side? Inquiring mind wants to know... (and there are front and rear coils for the 4 zone system, but again - each evaporator coil provides the cooling for both left and right sides..)

 

DIY with AC gauges on R134A systems is a tad risky. It's very easy to overcharge a 134A system - the range of correct fill is much smaller then it was with R12 systems. The real test is the temperature drop across the evaporator coil.. and the output temperature on full cool.

Since one side IS cooling (and it sounds about right on temperature, a 20F drop in temp) - AND - you got a code of "2600 - Temperature flap servo motor rear right" - it seems it's pretty much screaming at you to check that the servo motors are working correctly. I'd do that before even thinking about playing with the refrigerant fill - nuking the compressor could get awfully expensive on this vehicle..

 

Cool. So since I have a 4 zone system, I must have front and rear coils (excess water drips down under the car, in both front location and near teh rear driver tire).

Since you say each coil provides cooling for left and right, it would make sense to assume that cooling works.
I have durametric and did testing on the air condition. There are many tests but is there a specific type of test that could tell me more details of how the servo is working? There is a screen which tells you values when teh servo is changing but I do not think these fields are labeled (I am essentially staring at four boxes at bottom of window which contain values that change in some of the fields).

 

Yes - you have front and rear coils. And I would assume based on your temperature readings that the basic cooling function is working. What isn't working is the temperature function.

As far as what the Durametric is telling you - dunno. You might try contacting them. I've never bothered looking at the servo display screen with my Durametric. Or you could try eyeballing the servos (perhaps with a finger on them to feel movement) when you change settings and see if one never does anything.

One other thought - it might be worthwhile to bring this discussion over to RENNTECH.ORG (and become a paying member) since there are several Porsche mechanics who hang out there and usually are able to give good answers to questions like this. It's a less "social" site and a more "technical" site. There is a thread that might be of interest there: http://www.renntech.org/forums/topic...s-have-failed/ and I'd suggest searching before asking, your problem may have already been addressed.

 

More threads I found by searching on "servo":

http://www.renntech.org/forums/topic...vo#entry121778 - good details on where to find'm and how to tell if one is kaputski.

http://www.renntech.org/forums/topic...age__hl__servo - your problem isn't uncommon.

http://www.renntech.org/forums/topic...vo#entry219604 - hmmm.. looks like you've been there. You might want to bump this to see if someone can help.. but basically it seems as if it's either the controller unit (center of the dash) - $$$ but easy to replace, or a servo motor ($$ but harder to replace..)

And the hint in the one thread of swapping the power feeds to see if the problem moves with the feed or is only in the servo will tell you if it's $$$ or $$. You don't even need the Durametric to do that test, you just have to be comfortable standing on your head in the passenger seat.

 

BTW - looking at your failure mode (BOTH right side front and rear are warm) - I'd bet on the controller. Has to be a common failure point for both circuits.

Can we assume you've checked the fuses?

 

I wouldn't bet on the above hypothesis. and rush out to buy a controller just yet.

There are 2 controllers, one for the front a/c circuit and one for the rear a/c circuit.
Each CU controls their own set of either front or rear servos and blower fans. Each CU is independent of the other.

The easiest maint action I would try is first reseating the elex plugs on each controller, and if still no joy, go play with the servos.

The front blower regulator feedback fault can be checked via Durametric.
Does the front blower sound normal at different fan speed selections?

 

The front blower seems to function just fine. I have not paid extra attention to it, but will be sure to check this today asap (when my kids are at football practice for sure...lol).
But fromw what tests I did, and from usage, I did not notice front blower blowing less/more than the other vents when switching between them.

You refer to a part called controller. I guess you are referring to the part in the front dash and center console (for 4 zone ac), with the buttons and dials to set blower speed and temps, etc, right?
My service manual refers to it as air conditioning system regulator. I want to ensure these are same part. My service manual may be cheesy, so I want to make sure this is it.

 

here is a pic of the regulator my manual speaks of.
I have not found the rear one, but assume it is the same type of regulator that is mounted in rear of the center console for the car (4zone).

 

The regulator that your fault refers to is the blower fan regulator that is located behind the glovebox above the blower motor. Not the same as the A/C control unit/ headunit in the dash.

 

The PET wiring manual refers to the control units with the temp and fan speed switches on them as "climatronic control units".
Benson J correctly states that the motors have separate regulator for the fans, they are called "blower control unit" in the PET wiring manual.

There is a feedback line that runs from the blower control unit to the climatronic control unit.
One scenario would be if the CCU is not seeing this feedback, whether it is not coming from the BCU, or the CCU is not seeing it, this would log a fault.

 

...regarding code:
353 - Feedback from blower regulator front - Value below lower limit value

If this was a defective part, would I be experiencing no blowing at all from any front vents?
Or would this be something that would maybe slow down the blowing but not necessarily eliminate it?

Trying to determine what I should be looking for. I did try the tests, tried to feel the blowers. The front does have blowing, it is hard to tell if the right side is weaker than front.

...regarding code 2600:
where exactly is that servo motor located?
Trying to get a good picture of location but my cheap *** service manual has a hard time communicating that to me.
From above posts, it seems to be to the left of the glove box, up near the blower vents(???)

My questions are:
- how do you get to it to feel/replace?


Today I will hook up the ac gauges to see what my hi/lo line pressure is compared to charts in the service manual. Will go from there.
Any further advice let me know as I can use all guidance/help I can get on this (my first porsche and I do not feel like screwing it up)....lol.

 

Here are more details on my testing of the AC using Durametric:

Entered the test section of the sw.
started all tests sequentially (and apparently it captured info in a log).
Here is a good portion of tests ran, with results.
To understand results, in v6 of the sw, you are staring at 4 text box areas, each with various numbers in them depending on test.
The top value seemed to be the upper threshold value. The bottom value seemed to be the lower threshold value.
The 2nd from top seemed to be the actual read value compared against upper threshold.
3rd from top seemed to be actual value compared against the lower threshold.

Here is a diagram to help understand the above mumbling:
___________________________
| Upper threshold value.... xx.xx|
-------------------------------

___________________________
| Actual Upper Val for test xx.xx|
-------------------------------

___________________________
| Actual lower val for test xx.xx|
-------------------------------

___________________________
| Lower threshold val........xx.xx|
-------------------------------



FP = Front Passenger
FD = Front Driver
RP = Rear Passenger
RD = Rear Driver

OK means values in 2nd box seemed to change to match the top box values. Values in 3rd box seemed to change to match the value in bottom (4th) box.
I assume this sw changes the values to ensure the part in test can get to the upper and lower values.
Test List:
servomotor footwell flap fd = ok
servomotor footwell flap fp = ok
servomotor for central vents fd = ok
servomotor for central vents fp = ok
servomotor for side vent fd = ok
servomotor for side vent fp = ok
servomotor for fresh air/air - circulation flap = ok
servomotor for defrost flap = ok
activation of regulator for - fresh-air blower =
coolant pump activation = ok
temperature flap servomotor fd = ok
temperature flap servomotor fp = values do not change in middle boxes-BAD?
servomotor for volume air - flow flap fd = ok
servomotor for volume air - flow flap fp = ok
rear left air vent on tunnel rd = ok
rear right air vent on tunnel rp = ok
b-pillar servomotor drv = ok
b-pillar servomotor pass = ok
activation of regulator for - circulating-air blower = only bottom value (3rd box) changing...top (2nd box) stays at 0 v.
END


So what we have is 2 tests that I see an issue with:
temperature flap servomotor front passenger
activation of regulator for - circulating-air blower

Would it be safe to assume these tests prove the two parts need changing or is there more pd to be done to be more sure?

 

Ok. Did the AC gauges test too. Here is what I found.

ambient temp 72f or 22.2c
4zone AC unit in car
2005 cayenne turbo
Close doore and roof, open front windows only
Connected gauges
Started car and idled for about 5 minutes
Revved up to 2000rpm
At that rpm, readings were:
At high side: 152 psi or 10.48 bar

My service manual called for low threshold of 10 bar and upper threshold of 13.50 bar at that ambient temp.
Looks to me I am at low threshold now.

Can anyone comment on these numbers? I am hoping a small add of 134a will bring me to about 12 bar to see if that affects AC function. Still pretth positive that the se rervo may need replacement but this coul DC offset the
Seen behavior.
As always, thank you for your input.

 

Any update on this? Was your refrigerant charge low?