after weeks, I confirmed that the car came with the wrong climate control module. I plugged the right one in today, and the compressor clutch is engaging. Good so far.

But no cold air.

Had the car at a repair shop, but they could not service the AC:
a) compressor not kicking in back then (wrong module, see above)
b) not the usual small/big, low/high connectors on the 1996 A4.

Is there a way for DIY charging without the 'small' (low?) pressure port?
If DIY not practical, what does the shop have to do? I read about disconnecting at compressor and putting a special adapter in? If so, how is it called/part number?

 

Also, assuming that the compressor has not been running for a while (not sure when the wrong module was installed, estimate is 15 months at least), what else (aside from low pressure in the system) could cause the AC not blowing cold? According to the shop, the system had pressure (not leaked empty).

 

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ok here's the real deal with the '96 Audi A4 2.8L ....all there is on the A/C system is a "high" pressure point to charge the system from unless you get "http://www.amazon.com/Mastercool-MAS.../dp/B000FN4990" The best option is to just take it to a shop and have them do it. I took mine in 2 days ago cause I couldnt find crap on the net about the 96 A4 untill yesterday. it only cost me $100 for them to do everything the best way and the complete way. That includes evacuating everything in the system, including air, moisture and old oil and putting new oil and freon in. I'm not sure if they fixed this issue in the 97 but I know they did for the 98. In fact I have a bunch of parts off a 98 and both high and low pressure lines have the couplings to the left of the battery. I was thinking about replacing them but then I remembered the low side switch and where I would plug that into. I dont know where that switch is on other cars. so it can be done but I'd have to replace more than just those 2 lines. hardly seems worth all that hassle when the shop only charges $100 to do everything through the high side port.
So now that I know about that adapter I will buy one for next time. but like I said earlier, $100 is cheap to make sure there are no leaks and there is no junk in the system. But if you know ur system is clean then go buy that adapter and a can and do it yourself.
only prob for me now my compressor isnt turning on.... so now I have to tackle that prob hopefully its just a bad switch somewhere and not the compressor itself. I have 2 others that I can put in there but then that means I will lose all the freon I just put in.

 

After I found out that the 96 A4 does not have the regular 2 connectors, I took it to my shop as well ("let them figure it out"). They first were baffled, then spent time searching for the low pressure port. Finally gave up and decided to do it through the high pressure side. But then we noticed that the compressor clutch is not kicking in (even with low pressure switch jumped). Further diagnosis revealed that the clutch is not receiving a signal.

At that point I stopped the work, since I had a bunch of climate control error codes (that - as it turned out - were caused by one of the previous owners installing a module that does not work with the car).

I now fixed all the codes, compressor kicking in.

I bought the adapter.

I dropped the car off at the AC shop yesterday so they can service it today.

 

How did you fix the codes, replace the controller, or reset them with VAG-COM? My sons car is having similar issues, the major code is the High pressure switch being open/short to ground. His car is a 2/96 built A4 Quattro. I know there is freon in the car, just don't know how much (although I'm not getting the low pressure fault only the high pressure one) I've replaced the high pressure switch once and still have the same code. I replaced his controller (which might be part of the issue) last year with a used one from a 97/98 car (forget which and I'm going to pull it out tonight to see what model it is) and I noticed when i did it, the instrument lights on it seem to work backwards from all the other instrument lamps. The controller lights are on bright with the headlights off, and dim with the H/L's on. I'm also getting those open circuit footwell temperature codes 1296/1297 on this unit which makes me think its the wrong one for the car since the 96's don't have these sensors.

I pulled his original controller (was in the car when he bought it last year) out of the trunk this morning and its an 8LO 820 043 B unit, but it was built on 09/06/97, so even it has been replaced sometime in the past. The old one is going back in tonight, the R134 gauges are going on the fittings and then I'm going to see if the pressure switch is really bad, or if its the controllers fault.

 

First question: If you have 2/96, there is a good chance you have the NipponDenso compressor like I have.

With this compressor, the ONLY climate control module that works is the "H" (my trial and error, and instructions in Bentley). I could NOT code any of the other modules (my car needs 00162 for being a 1996, 6 cyl, US model).

I have tried 3 different (my car came with a "D", likely swapped in by the used car dealer who also took out the bulbs for the warning light for CEL, Airbag, ABS (all not working)).

Once I located a "H" module, all codes disappeared.

I also ordered the mastercool 82272 adapter (to give me the 'standard' low pressure port; install in place of the low pressure switch, jump the switch) and car is at the AC shop today for full diagnostic, flushing and charging.

(Hopefully) the only thing left (on the AC issues) for me to do is replace the burnout 4 bulbs (2x 2 Watt, 2x 1.1 Watt) on order (newer modules have LED for illumination on the circuit board itself).

 

Thats what I was afraid of. The one in the car now is most likely going to be an 043B one as well because I've learned to check the number on the parts in the car before getting a new one, and i put that one in the car about 5 or 6 months ago. I've got an 043H unit on the way, guess my son will have to sweat it out for another week. Maybe I'll try to recode the 043B to 00162, its 01462, or something like that now, can't hurt anything and i have a spare if it melts down.

At least your dealer removed your warning lights, my sons car's lights were burned out from being on so long. The results of one bad wheel speed sensor, one engine temperature sender, and the EGR valve lo flow warning that still pops up every 3 or 4 weeks now. Fixed everything els, just haven't brought myself up to pulling the EGR valve off and rodding out the passages in the manifold.

 

Found the break point for the Zexel to NipponDenso compressors, its 8D127955. That VIN and higher have a NipponDenso compressor without the compressor speed sensor, any VIN lower than that has (had) a Zexel compressor with the speed sensor.

 

Ok, got the new (to me) 8D0 820 043H module installed. Originally came coded as 00062 and it was telling me I had an open circuit to the A/c compressor clutch so I though i would have to do some trouble shooting of wires, which is not my favorite activity. But I recoded the module to 00162, and cleared the codes to see if it made any difference and it came back with no codes present but the A/C still would not engage the clutch on the compressor. I did the output test and the clutch clicked on and off like it should, put the unit into defrost and the clutch picked up so it is functioning semi correctly. It was 56 degrees and misty while I was doing this, and I had the temperature set on LO so maybe the system read the inside temperature and decided it was cold enough and it didn't need the A/C to run. Will go back and check it again when its hotter outside to see if its going to work, but it is at east partially working now, where as before nothing would get the compressor to engage, short of applying 12v directly to the clutch power wire. The display on the new unit is dim, but the 043H unit has 4 replaceable bulbs on the outside ot the back of the face so its probably just a blown out bulb or 2 on the back.

So I guess this is verification that the 8D0 820 043B and/or 043D climate control modules DO NOT work in a 96 A4.

 

"H" module a must for DENSO and 1996! (Can't speak for other combinations).
Softcode to 00162 (fuer 6 cyl, US model; don't think there is a 1996 4 cyl model).

If clutch kicks in: rules out low pressure in system (otherwise, jump the low pressure switch with office clip).

No error codes at all?

May check if you inadvertently pulled out the flat connector to the fan (would throw code I think, since output test can activate it), or flat connector from dash temp sensor to wire harness (any readings on that sensor)?

With no codes: system should run.