JBPorscheOwner

My wife and I just bought a used, one-owner, black 2011 Cayenne S with the Premium Plus Package. It has 89K miles on it but is in excellent condition. Due to my wife's medical condition (hyperhidrosis), when my wife drives the vehicle, she HAS to have cool A/C air blow sufficiently out both the driver's side dash AND floor vents simultaneously. When air is set to blow out through the driver's side dash OR floor vents, the air flow through either the dash or floor vents is plentiful. However, when she sets the A/C air to blow through BOTH the dash and floor vents, very little air comes out the driver's side floor vent. Furthermore, when air is directed through the driver's side dash and floor vents, the little air that does come out of the driver's side floor vent feels slightly warm vs. cool/cold. The A/C air flow to the PASSENGER side is fine in every way (dash-only, floor-only, or dash and floor simultaneously). Also, other than the driver's side floor vent, the A/C air temperature feels cool/cold out all the other vents.

Any ideas? My wife literally cannot drive the vehicle unless she can get adequate air floor through the dash and floor vents simultaneously. Is a software adjustment available that reduces the amount of air coming out of the driver's side dash vents so more air can be directed through the floor vent?

Jack

deilenberger

Jack,

Can I assume you've tried dropping the set temperature on the drivers side when the airflow is inadequate? That should do three things:

1. Change the temperature of the air
2. Increase the fan speed
3. Change the flap that directs air to the left/right of the vehicle to favor the left side (there is only one fan, so part of the increased velocity on either side is caused by the distribution of the air.)

If you have a 2-zone HVAC (no controls in the back of the center console) - you might try closing the rear vents that can be closed. Those are the vent in the B pillar that is at about head level, and the center vent. Both have regulating flaps on them. Closing them will increase airflow to the front vents, since in a 2 zone system the same air circuits are shared by the front and rear.

If this doesn't help you - then it's time to make sure all the flapper motors in the HVAC are working like they should be. You'll need access to a Porsche specific tool to test this. The dealers PIWIS will do it, and the iCarScan tool can do it (I've played with this somewhat excessively on my '11 CTT.)

Using the iCarScan there is a test that can be activated that exercises each of the motors and tests that it achieves it's full range within a permitted time. I have one flap that fails - even though it's moving as it should.. apparently it fails for time to make the move.

First off - I'd try closing the rear vents though - that's the simplest and most cost effective thing to try.

HTH,

BTW - thought of one other thing - there is a setting under vehicle settings for the overall HVAC velocity - it's user accessible. You have to dig down in the menus a bit to find it, but it's there. That might provide more air - not necessarily colder air.

JBPorscheOwner

Thank you very much, Don, for your fast response! Yes, we have tried setting the air temperature all the way to "Low" with maximum fan speed.

When you say change "the flap that directs air to the left/right of the vehicle", if you are referring to a single flap that directs air to the left or right inside the vehicle, where exactly is that flap? Our local Porsche dealership is trying to troubleshoot the issue now but they are just going by how the air flow "feels" to them (not very scientific). My wife's feet knows whether or not there is cool air coming out adequately or not. I asked the dealer to see if they have any air flow and/or temperature standards they could use to test the A/C's output. They are supposed to update me tomorrow. The additional information you provided me will help me to be more prepared when I presumably talk with them tomorrow. Everything you wrote makes sense to me.

BTW- When you referred to your iCarScan test on one of your vents, what did you mean by, "it fails for time to make the move"?

Jack

Jack

deilenberger

I just spent some quality time with the manual.. (all 11,000 pages of it..) There isn't one servo.. it appears they control distribution velocity by changing flaps that control each outlet basically..

There are flaps for the left and right center vent outputs. There are flaps for the top-dash center outlets, left-right
There a flap for the defroster
There are flaps for the right outer dash level vents, left-right
There are flaps for each footwell - left-right
There are flaps the temperature for each side - left-right
There is a flap for the recirculating/fresh air function

All in all - it appears there are 14 servo's.

It must all be controlled by a very complex controller..

There are also 3 different duct temperature sensors, including ones for the left and right footwell vents. If the sensor in the left footwell duct isn't working right - or out of position - that might account for something.

OH - one thing I just remembered.. really bizarre.



On the first 958 series Cayennes there were complaints that the HVAC system would start out putting out plenty of cold air, but after about 5-10 minutes the amount of air would drop off and the temperature of the air would rise - especially on the left side.

The reason was really odd.

There are four clips that hold the center face level vent in the dash. The clips pass through the plastic that makes up the duct behind the actual vent you see.

If the owner had restricted the face level venting in an effort to redirect air elsewhere (with the **** on the center vent), cold air would be forced out the hole the clip went through and right onto the back of the left side temperature sensor, which was then fooled into thinking the air temperature out of the footwell was way less than it actually is. So the system adjusted the temperature/velocity accordingly (and wrongly.)

The condition was worst when the center vent flow was blocked by the "shutter" sort of thing inside the vent (controlled by the **** in front) - but it was also found to happen, just not quite as badly even if that vent was open and the front vanes on the vent turned toward the driver.

The fix was a felt self-adhesive pad to block airflow around the clip opening in the vent.

I'd almost bet that's what's happening.

Takes about 10 minutes to fix. EASY fix. Remove vent, put some tape over around the clip opening, install vent. I used some self-adhesive foam rubber I had kicking around.

There is a tech bulletin about this somewhere.. I'll see if I can find it.. but... bet'cha that's it..

Couldn't find it - but here is a video on how to R&R the center vents:


Here are the clips (circled in orange - from the video above..):

JBPorscheOwner

Thanks again, Don! I will pass the information on to my local Porsche Dealer so they can check it out!

Jack

deilenberger

Found it:






Show that to the service department..

JBPorscheOwner

Will do, Don! I was hoping for pictures, but didn't want to push you to do more than you already have.
Hopefully, all the information you provided will help them to find and correct the problem(s).

I will update you after I know something further...

r553

I have noticed that the flow is reduced from the dash vents when you press the foot well button. They are stealing flow from the dash vents to provide flow to the foot well. I leave the foot well selection off when driving the car. The cooled seats are helpful but have a mind of their own as far as operation goes. YMMV.

JBPorscheOwner

Hello, Don! I hope you are doing well.

To update you, despite preparing and providing our local, small-market Porsche dealership with:
1) a detailed cover letter explaining exactly what HVAC airflow problem our Cayenne has (only a faint/trace amount of air flows through the driver's side floor duct when the driver's side air flow control is set to blow air through the dash and floor ducts - despite the HVAC blower fan set to the maximum fan speed and the overall HVAC airflow set to the "strong" setting in the PCM;
2) the Porsche Advanced Technical Information bulletin you provided me;

after the Cayenne spent eight business days at our local, small-market Porsche dealership, all their service technician previous did prior to today to attempt to troubleshoot the floor vent issue was apply the felt tape referenced in the Porsche's ATI bulletin, which I brought to him through you, to the driver's dash vent clip area and confirm that the air temperature coming out of the other vents was 48 degrees. Today, only at my insistence and perseverence through our service adviser did the technician allegedly ran Porsche's PIWIS calibration scan/tests against the air ducts. However, I have very serious doubts the PIWIS test was ever performed properly against the duct actuators as my service adviser initially claimed their technician ran the PIWIS test immediately, but only after 5+ days of me repeatedly asking him if he was sure the PIWIS duct control test was performed vs. just running their general-purpose tests against the vehicle (presumably via a ODBII-scanner) did he finally "double check" and admit they previously only ran their general purpose vehicle condition scanning tool and that no duct-specific tests were previously performed. For what it is worth, their general scanning tool showed the vehicle to have no problems whatsoever.

Today, after our service adviser claimed their technician 1) used the PIWIS scanner to successfully "calibrate" the vehicle's air ducts and 2) completed applying the felt tape recommended in the ATI-bulletin to the driver's dash-mounted duct, the technician claimed in his written report that the very faint amount of air that blows through the driver's side floor duct when air is set to blow through the dash and flow is "normal" and consistent with other Cayennes - and other vehicles in general for that matter!

However, when I picked up the vehicle late this afternoon and asked our service adviser to feel the air flow coming from the driver's side floor duct when the air is set to blow through the dash and floor vents, he acknowledged that only a trace amount of air was blowing through the driver's side floor duct. Our service adviser also acknowledged that, as I told him, the air flow coming out of the passenger side floor vents was much higher than the driver's side. As I told our Porsche service adviser, I have owned many vehicles of different types over the years and have never owned any vehicle that has less air flow through the floor duct when air is set to simultaneously blow through the dash and floor,

Thus, after the vehicle spent eight business days at our local Porsche dealership, my wife still cannot drive the Cayenne because she needs a reasonable amount of simultaneous airflow through the dash and floor vents! As a result of all this, I now have zero confidence that our local, small-market Porsche dealership will ever be able to help us resolve this driver's side floor vent issue.

If you and/or others on this forum don't have any other suggestions, my next step is to take the Cayenne to another local service shop who specializes in German cars. The owner/manager at the other German-car-service shop tell me they will do whatever it will take to troubleshoot and resolve the problem, including outfitting the vehicle with a stronger blower motor, etc. if that is required.

By the way, this evening, at your suggestion, I closed off the vent at the rear of the center console that services the rear driver-side seat. Unfortunately, doing so only marginally increased the air flow to the driver's side floor duct.

Additional Questions:

1. When the air is set to blow through the dash and floor vents, can the air flow be adjusted to allow more air to flow to the floor ducts? If so, how?
2. Is there an air-volume-test (similar to testing a home's HVAC duct) that can be used to test the amount of air coming through the driver's side floor duct to determine if it meets the recommended standard or not?
3. Because there seems to be a fair amount of airflow-related noise at the lower center portion of the dashboard near the firewall when air is set to blow through the dash and floor, is there a relatively easy way to determine if the HVAC ducting that services the driver's side floor duct has come loose somewhere under the dash? For example, can some type of "smoke test", which is typically used to detect vacuum leaks, be used to see where any air flow might be leaking through the HVAC system?

Any other suggestions? Any additional thoughts you have would be very appreciated!!!

Don, you have helped us more than our local, small-market Porsche dealership has!

Jack

deilenberger

Jack, it's late - so just a quick suggestion, I'll think on the other questions and get back to you tomorrow.

I would try dropping the panel under the dash and making sure the plastic duct is connected to the vent outlet from the HVAC box. If it's like the right side (and the 955 series vents) it's a simple press-on over an outlet, and it certainly could come loose if someone was working under the dash for some reason (like for the brake-pedal recall..) You can easily check if the outlets from the duct are lined up with the holes in the panel under the dash.. that doesn't require removing the panel. If they aren't - that's a sure indication the duct isn't installed correctly.

I haven't dropped that panel - but I can't imagine it being that difficult (the passengers side can be dropped in about 1 minute..)

Also - you have gone into the vehicle settings on the PCM and set the HVAC for high output right? (I forget the exact term they use - but there are three levels of fan output..)

Get back to you on the other questions tomorrow.

JBPorscheOwner

Thanks for your quick reply, Don, regarding checking the plastic duct that is connected to the vent outlet from the HVAC box. I will add that to my list of things to check out.

As for the PCM's HVAC output setting, it is already set to "Strong".

I look forward to hearing back from you regarding my other questions and any other ideas you may have after you get some rest!

Jack

deilenberger

Answers to the questions:

1. Yes - by partly or completely closing off some of the face level vents. Note that there is a vent in the back of the B pillar - a face level vent for the rear passengers. You can use the rotary **** on these vents to close them off. The center vent won't completely close off - it has a function that if the **** is all the way closed - the top vent on the dash takes it's place (complete with a stepper motor control to accomplish this.. talk about overkill..)

2. None that I've seen in the manual. It would be difficult to do since there are a multitude of vents that would have to be all measured at the same time (since measuring one would partly block that vent off and force the air out of the other ones.) There are temperature and pressure tests that can be done to make sure the cooling system is cooling as it's supposed to.

3. I suppose you could do a smoke test for the HVAC, although I've never heard or seen it done. I think physically examining the junctions would be more effective.

BTW - just as an aside. My '06 C/S was notable for having very little heat in the driver's side footwell.. and I never solved that issue, but I also never bothered dropping the panel under the steering wheel to look. The '11 has adequate heat and airflow on both sides, so.. it hasn't been an issue for me.

JBPorscheOwner

Thanks for your additional feedback, Don. To clarify, our 2011 Porsche Cayenne S, which has a V-8 engine, the Premium Plus Package, and a 2-zone HVAC system, does not have ANY vents anywhere on any of its pillars. For its rear passengers, the only vents that provide direct airflow to them are those at the rear of the center console. I wish it did have additional vents for rear compartment passengers. I suspect pillar vents only come with the Cayenne's optional 4-zone HVAC system (at least for the 2011 model year).

Jack

deilenberger

Jack,

I didn't realize the 2 zone didn't have face level vents for the rear passengers.

Here is a diagram of the ductwork on your Cayenne (2 zone system)..

Looking at it - I wonder what would happen if you stuffed a towel into the outlet under the drivers seat (the one for the rear passenger.. PN-5) that air would have to go somewhere right?

JBPorscheOwner

GREAT information, Don! You 'da man!

I did not know the Cayenne also has HVAC ducts running below each of its front seats to service the rear passengers!

At your suggestion, I just used some clean rags to temporarily plug the HVAC ducts that run under the driver's seat. Plugging those ducts definitely increased the airflow to the driver's floor ducts. After I plugged those ducts, I would say the output to the driver's side floor vent increased from about 1-5% of what would likely be normal output to about 20-25% of normal output. Since my wife is much more sensitive and needful for air at her feet than I am, I asked her to carefully and objectively compare our Cayenne's driver's side floor vent output now with our Toyota Camry's floor output when she also has her Camry set to output to the dash and floor. She immediately acknowledged she can now at least feel some air coming out of the Cayenne's driver's side floor vent, which is progress! However, even with the HVAC fan on the highest fan speed and the PCM set to the "Strong" airflow position, she said the output through the driver's floor vent is only about 20% of what her Camry outputs in the same situation. Thus, while your suggestion/theory moved "the needle" closer to our goal of normal air flow through the driver's floor vent when the air is set to simultaneously blow through the dash and floor vents, there must be something else wrong that is not allowing a normal amount of airflow to flow through the driver's floor duct in this scenario.

Additional Questions to Further Narrow This Down:
1. Are the front floor ducts pictured in another diagram? If so, would you mind posting it when you have a chance?
2. Where are you getting this great information? I would love to know where I can get my hands on the same information you have at a reasonable price.

By the way, I have scheduled to bring the Cayenne into a local German-car-specialty service shop next Wednesday to do whatever it takes to troubleshoot and resolve this airflow issue. Thus, if you have any additional suggestions that I could review beforehand, it would be extremely helpful!

Thank you VERY much, Don!

Jack