vtraudt

I have lots of issues with the HVAC system, see below. Is the module known to fail (common) or is/are other underlying issues causing the problems. Should I suspect the control module to have issues? If so, am I better of buying a used one (from $50 up) or sending my unit for repair ($50 plus shipping)?

- A/C compressor does not kick in (clutch does not get voltage), even with AC pressure switch shortened
- compressor clutch kicks in when directly supplied with 12V.
- A/C relay works
- only medium heat even with hot engine and highest setting
- flaps move

I get the following errors (most are always present depending on time between resets, but all return; see below).

Thursday,17,March,2011,12:29:04:22662

Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F

5 Faults Found:
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus

vtraudt

Decide (due to the number and what seems erratic appearance of codes) to get another used module for trail/error.

Installed module yesterday (unknown history, so I don't have final proof; could be just another bad HVAC module). When taking console apart, I noticed that there is a small fan, connecting to tube to the small center slot of the center console. In that slot is a temp sensor.

Below are the most recent codes before and after the switch. Some are the same, at least one is different (which could be from wrong install since it deals with the dash temp sensor):

The way I see it:
a) another bad module
b) module (or both) are ok, individual sensors issues
c) module (or both) are ok, sensors are ok, but wiring harness or connector or ground issue

Is it now time to attack each code individually?
Are those codes common (i.e. sensors fail)?
Aside from the 4 or so connectors in the back of the unit, and obviously the various sensors (with connector I assume), are there other elements/connectors in the path?
Where are the referenced (in the codes) sensors located?

New module 040911

Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 B
Component: A4 KLIMAVOLLAUTOMAT_D73
Coding: 04142
Shop #: WSC 06335
VCID: 27530F41EF6B

5 Faults Found:
00785 - Temp Sensor in Instrument Panel (G56)
30-00 - Open or Short to Plus
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent


Old module 031111
-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F

6 Faults Found:
00779 - Outside Air Temp Sensor (G17)
30-10 - Open or Short to Plus - Intermittent
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus

AudiMick

First of all kudos to you for sticking with this car. I think I would have arranged to have it "stolen and torched" by now.

Are you 100% sure you have a climate control module for a 96 in the car? This looks suspiciously like when a friend substituted a 97 version and it caused all manner of incompatibilities.

Have you checked the coding, they used that module in the Audi 90 and cabrio so the coding needs to be correct. There is a four digit code depending on the year.

It was listed on the OBDtool site but I can't find it now.

The small fan draws air from the cabin to measure temperature.

vtraudt

I did not check if coding is needed.
New seems to work (and show similar codes) as old. Where old seems to be manufactured in 1998 (but car is 1996; so may not even be the original?)

New module says:
Sticker:
D73-04-02
II 23.06.97 (note: car is 1996)
5HB 007 608-00

VAGcom
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 B
Component: A4 KLIMAVOLLAUTOMAT_D73
Coding: 04142
Shop #: WSC 06335
VCID: 27530F41EF6B

Old module says:
Sticker:
D75-03-02
I 04.05.98 (note: car is 1996)
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F

Sticker photos here:

Old:


New:

AudiMick

Is it possible that the original climate control had been replaced with the wrong one? The fact that it was newer than the car is intriguing.

Maybe someone could look it up on Ekta. Or some one here could look at their car.Here's the right one(off of a 90 cabriolet).

http://cgi.ebay.com/ebaymotors/93-95...Q5fAccessories

Bearing in mind this car's history I suppose it's possible.

You need someone to chime in with the correct module.4driver4 would know.