Re: '88 5000s Climate Control & Brakes

["Fred Munro" <munrof@isys.ca>]

-----Original Message-----
From: AMZ <amz@eskimo.com>
To: quattro@coimbra.ans.net <quattro@coimbra.ans.net>
Date: Monday, June 29, 1998 5:42 PM
Subject: '88 5000s Climate Control & Brakes


>I recently purchased an '88 5000s quattro and have some questions regarding
>the climate control.
>
>1. Is it just my car or do all of them heat better than they cool?  On a
>warm day (75 - 80 degrees outside), I can set the climate to LO and still
>not cool off the car enough to stand it with the windows up for more than a
>few minutes.  The air is like a lukewarm breeze.  Heat is no problem.
Could
>it be that the system needs a recharge?  How often should that be done?
>
>2. I thought a/c was supposed to *rob* an engine of power.  If I switch on
>the AUTO climate, the car suddenly seems to gain power.  If I turn climate
>off, the engine feels choked down just slightly.  Any ideas?
>
>3. Brakes:  When rolling backward down my driveway with ABS engaged, there
>*sometimes* is a slight metal clang when I apply the brakes gently.  It'll
>clang once or twice and then stop.  There is no noticeable problem with
>stopping power or pulling to either side.  Also, when I tested the brakes
on
>ice, the ABS worked, but made a metallic pulsing sound much like metal
>striking metal.  Without ABS, the brakes make no sound, but the car
skidded.
>The local VW (& formerly Audi) dealer's mechanic rode with me in the car on
>the test and said he thought nothing was wrong and that it was simply the
>sound an older ABS system makes.  True?
>
>The previous owner kept meticulous records.  Last a/c service was at 72k mi
>(replaced O-ring at restrictor, recycled freon, recharged system - Audi
>dealer).  The car currently has 105k mi.
>
>Thank you for you assistance.


    1. You have a problem with your A/C system. The air from the vents
should blow cold. The system only requires re-charging when a leak bleeds
off Freon or the system is opened for repairs. This is a common cause of
poor or no cooling, but there are lots of other possibilities.

    2.  An operating A/C system does rob the engine of power. For this
reason, the ECU compensates when the A/C is engaged to keep the engine at
the proper idle speed. What you interpret as increased power may be the
increased fuel flow with no corresponding load from your non-functional A/C
system. I would think this would only be noticable around idle, though.

    3.  When the ABS is activated, it is normal to hear a pulsing noise - it
kind of sounds like the brake pads have worn off and the backing plates are
digging into the rotors. Perfectly normal (unless the brake pads have worn
off and the backing plates ARE digging into the rotors!). What you are
hearing is the sound of the ABS system rapidly applying and releasing the
brakes on the skidding wheel(s). With a good ABS system (and the Audi system
is good), the noise is the first warning you may have that you are treading
on slippery ground.

HTH

Fred Munro
'91 200q  255k km