silvercayenneS

Starting a couple days ago, on a grueling ride to the beach, my car started hissing out of the driver side A/C vent and brake pedal. The hissing sounds like air slowly being let out of a tire.... ssssssssssss....

Both A/C and brakes function properly.

I have searched "hiss", "vent", "brake", etc. but don't come up with any results in the Cayenne forum.

Anyone know what this could be, or an easy fix for this, without involving a dealership/shop?

Thanks!

renaissance.man

Strange.. since the brakes and vents have nothing to do with one another. It can be difficult to localize these types of sounds. My best guess is a leaking brake booster since it is under pressure and located under the dash and through the firewall.

That is just an educated guess.

silvercayenneS

yes it's strange. The sound initially started coming out of the vents. Then over the last day or so started coming from the brake pedal area. In fact, it sounds like it's the brake pedal itself, or right behind it like you said.

griffiths

Its either a cobra in your dash or a leak from a vacuum operated device, example a HVAC actuator flap.
Next time it happens try changing the direction of the air (floor, center, etc.).

deilenberger

Aren't the flaps run by stepper motors (which are known to fail - but not with a hiss..) Watch for the cobra..

griffiths

Don,

I think you are right, they probably used NOS 993 stepper's (OH NO!),
or left over parts from an Audi Fox climate control.
Or, an air shock bag found a new home.

silvercayenneS

UPDATE: Turns out the sound was coming from behind the brake pedal. Dealership diagnosed as a leaking brake booster. $1212.24 + tax installed. $430.99/parts, $781.25/labor.

The weird thing is this didn't throw any code and the brakes seem to operate fine. I don't know if they will progressively get worse over the next week, but they feel fine now. The work is scheduled for next Friday as they couldn't get a loaner until then. The only consolation is that the loaners are 2012 Panameras

griffiths

So much for MTBF (mean time between failures).
Dam, I was kinda hoping to try out my new snake lasso.

Next time you at the dealer have um look at the center shaft bearing
support for the drive shaft.

And, save some bucks down the road, don't spill any coffee or soda's
on the shift console. The tiptronic magnet mat is such a silly design.

silvercayenneS

LOL MTBF -- I just got the car in Feb.... so right now my MTBF is 4 months.... I also get a low oil level light and random tire inflation lights in the queue...

silvercayenneS

...at this rate I can expect $3600/yr in repairs... that's OK... you gotta pay to play right?

silvercayenneS

Update: I canceled service. I really don't have 1213 to spend on a car that is still running. It pretty much has to be doa for me to drop that kinda cash on a car. If I had that kind of money I would have bought a new 911 or something. I am just going to keep hissing until something changes in the performance or function of the brakes. Until then, ksssssss cobra style.

renaissance.man

I would be careful ignoring a leaking brake booster. That is what creates pressure for your braking system. It might be mild now, but it would make me paranoid... we are ultimately talking about a safety issue here.

griffiths

Check your PM