the_duke

The noise is normal right after shutdown.

From the interwebs:

Many times a friend or customer will ask me to come listen to a strange hissing sound when the automobile is turned off.

Naturally, this is after running the system for a while on a hot summer day. Although this hissing noise, sounds like a bad noise, it's actually a good air conditioning noise.

The hissing sound is caused by equalizing pressure. When the car AC system is running there is a high side and a low side that's divided by either an expansion valve or an orifice tube. These two separate sides of the system are necessary for proper operation.

When the vehicle is turned off or the air-conditioning compressor clutch is disengaged the system will equalize the pressure. The hissing sound is the Freon from the high pressure side slowly feeding into the low pressure side and this is completely normal.

Y888

Thanks for the answer

omarcarbomb

when my wife is trying to get the S8 as cold as possible as quickly as possible using the Auto mode of the cabin thermostat she sets the controls to Auto Recirc with both zones set to low.

I noticed that the fan does not go full strength.

Meaning you can hit the plus button and increase the fan by 2 more clicks.

It is minor increase in fan and probably has just a placebo effect but it makes me wonder why it is throttled back and if you can increase the fan speed with VAG. I rented cars recently while traveling and they all blow max fan in max AC. they are not dialed back like the S8.

I have heard that in a home AC if the fan speed is too fast you can get humidity removing problems.

There is supposedly such as thing as too fast of an AC fan.
I would assume that applies to cars as well.

I don't think that somehow this is some solution to better cooling just something I noticed and couldn't explain to her.

soundbehindyou

SOLUTION TO MY PROBLEM:::: I took my car into Audi Dealership as independent shop did not want to touch it.....Audi charged me to purge the AC gas and refill.....they found two MO? Moe Doors?? not working...they are electronic signal boxes about 2 inches square that active via a signal to rotate a pin that opens or closes doors that carry air to parts of the AC vent system....(according to my service manager who I did not take notes from) there are as many as 20 of these devices??? that open or close vent airways depending on AC settings.
Now my car appears to be working properly and is cold again (although I still think the dash vents next to the side windows does not blow enough air but I may be wrong.
Only having 64k miles on my 2001 S8 I certainly hope this fixes the problem as it was a $1250 experience. THANKS TO ALL WHO CHIMED IN!!

2001 S8

Thanks for following up and letting us know the solution. Yikes on the cost!

Enjoy the air flow : )

davek4300

I know this is an old thread....BUT I just reversed to polarity/connection on my 2000 A8 - Bosch Replacement Blower motor. The connection before cutting out the plastic tab was reversed, the fan was spinning clockwise in blade direction virtually NO Flow, . Cut the plastic tab/key. Reversed the connection...now it rotates counter clockwise against the fan pitch , thus blowing like a $20 ***** (sorry couldn't resit that one)

Total thanks and a major time saver...bring on the summer heat and humidity....!!

DaveK

soundbehindyou

I had my problem fixed a while back. I had 3 or four of the "actuator doors" that receive a signal to open or close located inside the dash replaced. No independents wanted to touch the job....I had the Audi dealership replace them and have been good since.

2001 S8

Nice fix. I installed a new motor last November and always felt the air flow was weak. Pulled apart the the housing and guess what...fan was going in the wrong direction (blade direction). I used your method of cutting the plastic tab, reversing the connection and boom...air flow galore. Thanks for the tip audinutt & DaveK.

BTW: I purchased the motor from AudiUSAParts.com. I think all these replacement motors are wired backwards.