Annoying Ac Whistle

[Hobofob]

Hello, I own a 2004 Cayenne S.

When the outside temperatures increased, I noticed that when starting the car and when AC is working hard that there is a loud whistling noise coming out of what seems like left front dash vents. The noise slowly goes away when the car reaches the desired temperature. The noise is pretty loud and very annoying, it feels like AC is working against some sort of obstacle in the AC tubing ...

There was no such noise during the winter months.

When I open ANY window or door (depressurize the car?), the noise goes immediately away.

Any ideas? Thanks for help!

[mudman2]

You obviously did not read the optional manual. What you are hearing are the hamsters which control the vents. Some car manufacturers use electric servo motors for this job. The 04 you have had correctly sized hamsters when new but as they get older they get middle aged spread and are to big now hence the screaming. They need to be replaced with new hamsters.

Edited April 13, 2010 by mudman2

[rizzo]

I have old hamsters too...

[Hobofob]

Funny :) My problem is real and I am against animal cruelty, so other ideas are appreciated ...

[RFM]

The whistle is caused by air pressure inside the car, the pressure escapes through small cracks and holes which are in direct contact with the outside air (door and window seals). Behind the removable trim, left and right, in the trunk are two ventilation grilles which are covered by a rubber membrane, make sure the grilles are free of dirt, junk, etc. cut away a small part of the membrane such that direct contact occurs between outside air and car interior, the pressure will escape without that annoying whistle.

[RFM]

A second important spot to look at are the air entrance and exit in the front doors, sometimes the air exit holes in the doors do not/bad match with the air entrance in the B pillar (loose grill, damaged seal, door badly adjusted) You can check it out if you put some tape on the dashboard air exit/connection between door and dashboard, so that no airflow can pass through the inner door air channels.