I have spent weeks now trying to get the HVAC on my 1996 B4 A4 2.8 12V quattro to run. Still no luck.

During winter, the air did not get really hot. Sometimes it seem to heat ok.
Cold never works, compressor not kicking in, compressor clutch does not get signal. System seems pressurized, but no confirmed reading (no high/low nipples).

I later learned about modules and codes.

The car had other weired/not matching hardware (new heated seats that don't work with the car, transmission code from a 1998 (I replaced with correct year, aftermarket radio, etc.).

Hardware: NipponDenso compressor (w/0 G111 speed sensor I assume)
No high/low refrigerant service ports

HVAC modules:
The car came with a module 8L0 820 043 D module, manuf date 04.05.98. Soft code 04162.
That is the code for a 1997 A4, no G111 speed sensor, 6 cyl, US gas model.

I replaced the module with another 8L0 820 043 B, manuf date 23.06.97
Soft code 04141 (1997 code, 4 cyl). Recoded to 6 cyl.
Similar error codes.

I bought a 3rd module, 8L0 820 043 B, manuf date 02.06.97. Soft code 04162 (1997, 6 cyl).
Similar error codes.

Found in Bentley (but not clear to me):

"Zexel A/C compressors are installed from start of production. During m.y. 1996, Nippondenso type compressors are installed as a running change. These
compressors are not equipped with A/C Compressor Speed Sensor A/C speed
sensor G111 ." Checked: Nippondenso is installed.

"A/C Display Control Heads beginning with Part No. 8L0 820 043 should only be
installed in m.y. 1997 vehicles." (mine are all of that number)

"If a replacement A/C Display Control Head E87 is not coded after installation or if an unrecognized code was entered, code "04142" (Audi A4 4-cyl. - USA) is stored."

"Nippondenso A/C compressors must have A/C Display Control Head Part No. index "H" installed to allow coding "00162."

00162 would be the right code for NipponDenso, 1996, 6 cyl, US gas.
But "index H" modules are entirely different, only ones I say are in A3; and hardly any can be found. Does someone have a photo of a "index H" module from a 1996 A4?

The only "H" I found seem to have part number 4A0 820 043 H (not 8L0).
Is that number used for the 1996 A4 Bentley is talking about with "H"?

"8L0 820 043 after D: For all vehicles up to m.y. 98 without radio navigation system up to VIN 199999 of m.y. 1999 (lighting indirectly activated via terminal 58s)." ??? not applicable

"8D0 820 043 K or L: Version with single display (for vehicles with radio navigation system up to VIN 199999 of m.y. 1999)" ??? not applicable

"8D0 820 043 after M: Version with single display (for vehicles as of VIN 200000 of m.y.1999)" ??? not applicable

Depending on module, I get those codes:

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
00785 - Temp Sensor in Instrument Panel (G56)
30-10 - Open or Short to Plus - Intermittent
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
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus
00532 - Supply Voltage B+
07-00 - Signal too Low

 

Still not knowing if the wrong module came with my car (and that being the reason AC not working), I plugged in VCDS (VAGcom) and tried to read the blocks. 2 modules are 1997 ending in letter B, one is 1998 (came with the car) ending in letter D. I coded all three to the applicable code (04162 for A4, 6 cyl, USA). NONE of the 3 was able to read any values in any measuring block.

There is the chance that all 3 are bad, but my money is on all 3 not being compatible with 1996 car with NippoDenso compressor.

Bentley note refers to the need of a "H" letter module.

Can someone look up or provide the complete part number for the "H" module for a 1996 A4?

Is it the same same (sans the letter) as my current modules, which all start with
8L0 820 043 B (or D)

Or is the number different?

 

I noticed a the issues you mentioned when I swapped my '96 HVAC controller with an '01 to complete a double din swap. It seems Audi basically threw a bunch of parts together to get the '96 model year out he door, as subsequent years have the same units throughout. '96s went through many revisions so I am not surprised to see that parts that are used in later years are intact cobbled together in the '96s. Sorry ii cannot provide much help, but I feel your pain.

 

Looks like the H coded module I need is part number
8D0 820 043 H

Does anyone maybe have one around?

 

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