Audi A4 B5 1.8L Gasoline Engine Air Conditioning (Solved)

I have here an Audi A4 B5 from 1996 with a 1.8L gasoline engine; it should be an ADR model, but I'm not sure . The air conditioning is not working, and the fans in the engine compartment are not turning on. On the automatic climate control, the snowflake icon doesn't activate (it only lights up briefly when the snowflake button is pressed).
Manually powered compressor ---> The magnetic clutch engages, and the air conditioning cools.

Refrigerant amount: Correct. It was only missing 130 grams, but that wasn't the problem; it has now been corrected. Fuses also located behind the steering column cover. I.O. (In Ordnung - meaning "OK" or "in good condition").

I'm looking for a wiring diagram for the air conditioning system to help with troubleshooting.

What does the error memory say?

But if the snowflake disappears immediately, it usually means there's not enough refrigerant, or in your case, the control unit (STG) thinks there isn't, because the pressure sensor is probably defective.

I'm not sure if it's the pressure switch, so a wiring diagram would be helpful. VCDS cannot compete with climate.

T3Surfer wrote:

VCDS can't handle this climate control system.

But it has to, because these parts are definitely readable.

Hey everyone!

No, the climate control system, at least in the A4 B5 with gasoline engines, is not designed to be easily diagnosed.
Is it also stated like that in the documentation ?

Best regards from Munich!

EDIT: (I believe) until around model year 1996/1997.

Okay, I need the wiring diagram for that, and I'll check it without using VCDS.

It's been taken care of .

Could you also tell us what it was?

"If I have the box back and I've successfully gotten it working, then yes!"
Currently, the climate isn't important; the car is running fine.

Okay, so, the mechanic came to my place today for some other minor things, and he tried again with VCDS while the engine was running ---> and it worked!
I can't find the roof temperature sensor. Is it perhaps the sun sensor located in the center of the windshield, near the air vent?

What raises my suspicion is the value "-49.0°C" in field MWB 006, which refers to the "Fresh air blower."
and 007 1 position -48.0°C Headliner temperature

I suspect these are the reason why the compressor is being shut off; it's probably because something is causing the temperature to drop too low.
What are these things called in German? Okay, hier ist die Übersetzung:

"Unfortunately, my English is terrible."

Here:

Address 08: Climate Control/Heating. Label file: 4A0-820-043.lbl.
Control unit part number: 4A0 820 043 H.
Component and/or version: Climate control system, full automatic D05.
Encoding: 00060
Operating number: WSC 02315
VCID: 1E37896A9AACF49
Sure, here is the translation of the text from German to English:

3 errors found:

00786 - Roof temperature sensor (G86)
30-00 - Disconnection / Short circuit after positive terminal.
00800 - Blower temperature sensor (G109)
30-00 - Disconnection / Short circuit after positive terminal.
00603 - Actuator motor for footwell/defrost flap (V85)
41-00 - Blocked or Unpowered.

"Die Sonne scheint hell, und die Vögel zwitschern fröhlich. Es ist ein wunderschöner Tag, um spazieren zu gehen oder ein Picknick im Park zu machen. Viele Menschen genießen das gute Wetter und verbringen Zeit im Freien."
"Die Sonne scheint hell, und die Vögel zwitschern fröhlich. Es ist ein wunderschöner Tag, um spazieren zu gehen oder ein Picknick im Park zu machen. Viele Menschen genießen das gute Wetter und verbringen Zeit im Freien."


Address 08: Error cleared.
"Die Sonne scheint hell, und die Vögel zwitschern fröhlich. Es ist ein wunderschöner Tag, um spazieren zu gehen oder ein Picknick im Park zu machen. Viele Menschen genießen das gute Wetter und verbringen Zeit im Freien."
"Die Sonne scheint hell, und die Vögel zwitschern fröhlich. Es ist ein wunderschöner Tag, um spazieren zu gehen oder ein Picknick im Park zu machen. Viele Menschen genießen das gute Wetter und verbringen Zeit im Freien."


Address 08: Climate/Heating (4A0 820 043 H)

20:35:28 Block 006: Outside air temperature.
19.0°C Outside air temperature.
22.0°C Fresh air intake duct.
19.0°C Temperature at the front bumper.
-49.0°C Fresh air blower.

20:35:28 Block 007: Interior temperature.
-48.0°C Headliner temperature.
28.0°C Instrument panel
59.0°C Engine coolant temperature.
58.0°C Engine coolant temperature.

20:35:28 Block 010: Compressor control.
0.0 Kickdown switch
0.0 Thermal switch
0.0 Compressor engagement
1.0 High-pressure switch

Try http://translate.google.de/ out.

Okay, I understand. Please provide the German text you want me to translate. I will only provide the English translation in the response.

Relatively satisfactory.

The only explanation I can think of for the sensor in the roof is that either the control unit doesn't fit the car or it hasn't been properly coded.

You can easily replace the fresh air sensor on the blower. Simply reach behind the blower housing from underneath and feel for the sensor and its connector. Disconnect the connector and then twist the sensor out using the bayonet mechanism.

If something is a bit fiddly, it will work, but the part number should be: 4A0 820 539.

"Mine was broken too, and the device started heating up excessively."

Rüdi wrote:

I can only explain the entry with the sensor in the roof by saying that either the control unit doesn't fit the car or it's not properly coded. You can easily replace the fresh air sensor on the blower. Simply reach behind the blower housing from underneath and feel for the sensor and its connector. Disconnect the connector and then twist the sensor out using the bayonet mechanism. If something is a bit fiddly, it will work, but the part number should be: 4A0 820 539. It was also broken on mine, and then the box started heating up excessively.

Car service: I tried using Translate, but it didn't produce anything useful.

Rüdi:
I tested this sensor, which is located behind the pollen filter, using a hairdryer, and it seems to be working correctly. The temperature reading for the "fresh air intake" increases appropriately, and the outside air temperature is also being measured correctly.
The heater is working normally despite some errors, but the air conditioning is not turning on.

I want to know what the two sensors displaying unrealistically low temperatures of -48 and -49 degrees are, and where they are located. My assumption is that these are the reasons why climate change is happening.

Quote:

... 006,0, Temperatures (outdoor) 006.1, *calculated externally, for display*. 006.2, Intake manifold, (G89) 006,3, Bumper (G17) 006.4, Cold air outlet. Okay, I'm ready. Please provide the German text you want me to translate. 007.0, Temperatures (interior) 007,1,Roof (G86) 007,2,Distribution panel (G56) 007,3,calculated,coolant temperature. 007,4,Coolant temperature, (G110) ... 010.0, Stati 010,1,Kick-down,,0 = Kick-down switch open\n1 = Kick-down switch closed 010,2,Coolant temperature, too high, 0 = Temperature sensor open, 1 = Temperature sensor closed. 010,3,Output,Compressor Engagement (to Engine Control Unit) 0 = Output: Air conditioning compressor engagement open 1 = Output: Air conditioning compressor engagement closed 010,4,High-pressure switch, (F118), 0 = High-pressure switch closed\n1 = High-pressure switch open

You have a private message.

Best regards, Rainer.

The atmosphere of B5 is becoming tense again .
I received a request to install a TÜV inspection and a different radio. During the radio removal, I noticed - see photo, that the previous owner had installed a C4 Climatic control unit in the B5. The old coding was 0060 (probably some kind of V6 in the C4), and I re-coded it to 00140. Eureka! The errors are gone, and the air conditioning is working.

Don't tell him when he picks up his B5, let's see if he notices.

Edit: Rüdi is absolutely right, how can one predict the future?
If it weren't for the radio, I would never have thought of it.
If the owner really wanted it to work back then, I could have simply manually reconfigured it using a separate switch, with low-pressure and high-pressure monitoring.

The ways of the Lord are inscrutable... and thank you for the feedback .