[s-cars] AC Troubleshooting Help needed

[bullitt at gwi.net]

Tom,

Thanks for the info.

I looked at http://www.sjmautotechnik.com/ and can only find info for the
5000's and no info on the codes or clearing them other than pulling the
fuse for the ECU, which probably does not do anything for the HVAC
diagnostics.  Let me know if you have more info on that.

Diagnostics:

The electric fan comes on when the AC is turned on - ok there.

There is a definate sound of the compressor coming on when the AC is first
turned on.  It then starts to cycle.

Codes:

You are right, that is a lot of codes.  I did monitor some of the flap
position channels and they appear to be working propoerly.  The target and
actual position match pretty closely on all of the channels that had been
reported in the trouble codes.  I think there could be an intermittent
problem there?


I thought the high pressure switch was the culprit also, now I need to find
out why it is being tripped. I was thinking that a blocked oriface could be
the problem, blocked oriface results in high pressure since and no cooling?


Other:

The guy fully evacuated the system and put in 38 ounces (he looked up the
capacity in some type of manual).  

He did use a gage on the low pressure side.  He said it appeared to be in
the right range when operating.  He did not measure the high side (probably
becouse it is a somewhat of a pain to get at with the belly pan and all.

Thanks

Jack


Original Message:
-----------------
From: Tom Green trgreen at comcast.net
Date: Tue, 18 Jul 2006 10:32:07 -0400
To: s-car-list at audifans.com, bullitt at gwi.net
Subject: Re:[s-cars]AC Troubleshooting Help needed


That's a lot of codes, Jack.
I think your system is asking for a little attention.  If you are not  
going to
use a VAG/COM for codes, Scott shows you how to read and clear codes
here:
http://www.sjmautotechnik.com/

Of course, clearing the codes isn't going to cool you down.  Most of  
these
will probably come right back.

Diagnostics:  Does the electric fan come on when the compressor  
cycles on?
Do you actually hear the clutch engage (you can visually see it  
engage also)
when you think the compressor comes on (you should hear the compressor
as well if you have the hood open)?

Codes:  Most of those indicate parts are wearing out or making bad  
connections.
Scott did have a link to a site with directions for repairing the  
little flap motors and
potentiometers used for position sensors.  Most are available online  
and not too
difficult to replace.  The 11.7 code for the G112 flap motor/ 
potentiometer is the
most difficult.  The 15.1 code repair note states not installed in NA  
cars.  I can
not locate any sensor, so I would ignore that one.
I would concentrate on the 22.3 code and why the high pressure switch  
cycles
(and interrupts power to the compressor clutch).  That is the only  
code I see that
should be fatal to system operation other than perhaps the blower.

How much R12 did your a/c man add?  Did he use gages to check high  
and low
pressure? or just abort because the system wouldn't stay on?

Tom

Original message:
> Date: Mon, 17 Jul 2006 22:11:20 -0400
> From: "Jack Gagnon" <bullitt at gwi.net>
> Subject: [s-cars] AC Troubleshooting Help needed
> To: "S-Car-List" <s-car-list at audifans.com>
> Message-ID: <GHEJJEIJNBDMAIDDEMMLGEBECGAA.bullitt at gwi.net>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Hello all,
>
> I need some help here.  I've got a 92 S4 and the AC is not  
> cooling.  It has
> been this way for about 1.5 years now.  With all this hot weather  
> lately and
> global warming coming, I need it fixed now!
>
> Last time I had it diagnosed, there were no leaks and was told it  
> needed a
> re-charge.  Last week I got the system evacuated and refilled and  
> still no
> dice.  The compressor cycles on and off bit the evaporator never  
> seems to
> get cold.
>
> I checked out hvac diagnostic channel 1 and got a bunch of codes
> (7.3,8.3,8.7,11.7,15.1,18.3,22.3). I don't know how long they have  
> been
> there and are probably some are a result of the AC man tripping the  
> low
> pressure switch to put the refrigerant (R-12) into the system.  He  
> filled
> the system through the low side by removing the low pressure switch  
> and
> connecting his tank right to the exposed fitting and then shrting  
> out the
> low pressure switch with a piece of wire.
>
> I put the system on low and monitored channel 52 and the compressor  
> comes on
> for 5 seconds and is off for about 20 seconds. the cycel repeast like
> clockwork. I can hear something change in the air flow when the  
> compressor
> kicks in, but the no cool air and the air flow sound resumes to the  
> normal
> sound when it is off.
>
> I think I need to clear the codes (anybody know how?) and run the
> diagnostics again.
>
> Here are the desciptions of the trouble codes listed above:
>
> 07.3 Ambient Temperature Sensor at Fresh Air Blower (G109),  
> sporadic open
>
> 08.3 Temperature Regulator Flap Motor Position Sensor (G92),  
> sporadic open
>
> 08.1 - 08.4: Temperature regulator flap motor will no longer be  
> controlled
> automatically; manual adjustment only.
>
> 08.7 Temperature Regulator Flap, sporadic block
>
> 08.5 - 08.7: Motor is cycled; software attempts to eliminate block.  
> Watch
> Diagnostic Channel 8 to see digital value for flap motor position  
> sensor
> (G92).
>
> 11.7 Central Flap, sporadic block
>
> 11.5 - 11.7 Motor is cycled; software attempts to eliminate block.  
> Watch
> Diagnostic Channel 11 to see digital value for central flap motor  
> position
> sensor (G112).
>
> 15.1 Back Pressure Flap Motor Position sensor (G113), static open
>
> 15.1 - 15.4 Digital value internally programmed for limp-home mode
>
> 18.3 Fresh Air Blower voltage, sporadic
>
> 22.3 A/C Refrigerant High Pressure Switch (F118), sporadic open
>
> Do I have a blocked oriface?
>
> Can anyone give me some advice here?
>
> Thanks
>
> Jack





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