Anyone did an AC recharge on the CTT yet?
I have a 4 zone ac in the car and have not yet looked under the hood for ac orientation, but wonder if anyone has done this and can share input/expereince/tips.
Noticed that my passenger side vents are not blowing as cold air as the driver side vents...still cold but not same.

Thanks.

 

That isn't a symptom of a system needing a recharge.. more likely a problem with the hot-water valve to the heater cores, or with the air-diversion flaps.

And are we correct in assuming both sides were set to the same temperature?

 

When temp set to identical temp in all sides of car (FT Pass, FT Drv, RR Pass, RR Drv), and all flaps were opened to same degree (full on), and vents are all directing air through same pathways (ie all front vents), the temp of air coming out of the passenger side ac is not as cold as the air coming out of the driver side vents.

Since I am not familiar with cayenne ac, I do not know if the entire ac system is driven by one system. If it is, there are other possibilities, but I need more info.
I have a service manual that I bought but it does not do as good a job with pd and explanations as I would have liked.

Hope someone can help provide some insight on symptom/locations for the cayenne ac system(s).

Thanks for the help.

 

There is only one AC compressor - so the entire system is a single system with multiple controls. Porsche controls the amount of cooling by two means - one is the compressor is a variable volume compressor.. it only provides the amount of compressed gas that is needed to adequately cool the evaporator coils. They then use heat from the heater cores (and there are multiple cores) to buffer the temperature. All of this is directed not only by the manual vent controls on the vents themselves, but also by motorized flappers inside the vent system.

There is only one temperature sensor for the 2 zone system (ie - front and rear combined system). There may be temperature sensors for the 4 zone system (seperate front and rear evaporator/heater coils). In either case - if it was the front or rear being different, this I might expect, depending on how well the temperature sensor is working.. but..

The description you give of the temperature being different between the left and right side face level vents leads me to believe the valves controlling the heater coils (there are TWO for the front, dunno on the 4-zone if that's true on the rear) - which can be switched independently depending on the setting of the temperature by the seat occupant.

If one of the valves isn't working the same as the other - the flow could be different, and too much heat is being provided to one side, causing it to feel warmer then the other side.

Not a trivial thing to diagnose. Being able to activate the valves manually requires at least a DuraMetric (I believe you can switch them open/closed - but would have to hook it up to see..) or the Porsche tester. One possible home test I can think of is to turn the AC compressor off (economy mode button does that) - then use a good digital thermometer to measure the air temp from the face level vents - with both sides set to the same temperature. If one is warmer then the other - that's the side that probably has the leaking control valve.

It's possible one of the valves doesn't fully close (not an unusual failure for these sort of valves - BMW's used to do it all the time) and that's causing your temperature differential.

As with most systems this complex - having the right equipment makes a big difference in being able to diagnose it, as does having someone with the skills required to troubleshoot it and not just start replacing parts.

Unfortunately - aside from one private mechanic I know - I can't suggest anyone with that skillset.. and more then likely very few dealers have mechanics with the skillset to troubleshoot complex HVAC systems.

If it's correctable by turning the temperature down on the warm side - that's what I'd probably do..

Good luck..

Oh - one other thought. I do believe Porsche may use electrically driven heater water pumps to control coolant flow through the heater coils.. one of these may be failing, making that side cooler then the other. Also a possibility. My tech manual is packed away at the moment, so I can't really look it up for you..