Climatronic & Clutch: Troubleshooting & Repair

I have a Golf IV, 150 horsepower PD engine. This car was assembled from parts of three different vehicles, meaning it was originally a TDI with front-end damage, and then received a new wiring harness, engine, etc. from a PD model.
Just a little background information.

The problem: The magnetic coupling of the Climatronic system is not being activated.

VAG-COM apparently doesn't display any error codes.

The VAG-COM output test controls the fans, etc., so I assume the control unit (located in the lower left of the engine compartment) is okay, because isn't it controlled by the Climatronic control unit?
I'm not sure now whether the communication is handled via a CAN/K bus or if it's individually wired.

VAG-COM also also measures the voltage of the 'A/C Clutch' as well... it's always 12.3V or 13.7V (when the engine is running).

When the magnetic coupling is connected (if the connector is plugged in), there are approximately 9 volts present. However, this voltage drops to zero when a resistor is connected between the positive terminal and ground.

If you apply 12V to pin 10 on the control unit (which connects to that pin), the clutch engages. Therefore, the problem likely isn't with the cable running from the control unit to the clutch.

Circuit errors caused by makeshift wiring repairs are certainly not ruled out, but we have been monitoring the system for two weeks and everything appears to be in order.

I just don't know what to do anymore, what else can I possibly do?

I thought it might be the initial stage (relay?) of the control unit, but that is sealed . Besides, we tried another one: Same error!

NOTHING ELSE:
VAG-COM displays a message like 'A/C Clutch switch-off condition' or something similar, but I don't have the exact wording. The value displayed is 1-12. What does this mean exactly, and which value should I have when the system is operating?

Please help, I really don't know what to do anymore.

Hello,

Condition 12 indicates that the engine control unit (ECU) has deactivated the compressor.
(The climate compressor can be switched off by the engine control unit and/or the automatic transmission control unit J217 via the output/input signal ("climate compressor control").)

Please post something.
- The coding of the engine control unit (ECU).
- Measurement modules 10 and 11 of the Climatronic system.

What type of transmission was installed?

Hey, thanks for the quick reply.
Okay, I can only take a proper look at it tomorrow.

Okay, first of all, the transmission is from a 4Motion model (although the rear drivetrain is disabled).

I'll check the measurement modules tomorrow.

What value does the A/C clutch switch off need to have for it to work? 0?

What surprises me is that even during the output test, the magnetic coupling isn't engaging. Isn't that strange!?

Hello,

Quote:

What surprises me is that even during the output test, the magnetic coupling isn't engaging... isn't that strange!?

No, because the same thing happens with the shutdown condition.

Okay, I was able to extract all of this information:
Climate-STG:

VAG Part Number 3B1 907 044C.
Soft Code. 01000
Comp. Climatronic C 0.7.0
Shop WSC 01317

Engine Control Unit (ECU)

VAG No. 038 906 019AQ
Soft Cod. 00003
G000SG1230
Shop WSC 31414.

- I was unable to find measurement blocks 10 and 11 using VAG-Com. It indicates that these blocks are not available.

- Single Reading also doesn't have channels 10 and 11 either.

(Am I doing something wrong?)

In the engine control unit (ECU), readings 10 and 11 (single readings) result in values of 1004 and 294, respectively.
But I don't think that has anything to do with it.

Then I also performed a self-diagnosis on the Climatronic system by pressing the key combination on the control panel.

I found a description in an Audi forum that suggests that in channel 52 (graphic output), the segments of the panel are essentially a binary output, which is the cause of the shutdown (the link is here: www.audiworld.com/tech/int5.shtml).
Unfortunately, I didn't have any success with that either, because their list only goes up to 61. My Climatronic only goes up to 51 or so, and I couldn't find that 'segment' thing on any other channel either.

Then I tried to re-code the Climatronic using VAG-Com (Recode 04000 => Ignition on/off => Basic Settings group 000 => Performed basic settings).

It didn't bring anything. With the car on and the engine running, the shutdown condition is 12 .

What else can I do?!

Both the Climatronic system and the engine control unit (ECU) have no relevant error codes stored. (Some time ago, there was an intermittent 'engine coolant temperature sensor' error.)

I'm desperate .

Hello,

The issue with the coolant sensor has been fixed (if the coolant temperature is too high, the compressor is also switched off via the engine control unit).

What does measurement group 2, value 4 indicate in the engine control unit (ECU)?

The sensor fault has been recorded twice so far. G62 was the error code, and it was intermittent. We then put the sensor on a trend and measured it. Everything seemed to be okay, and the fault hasn't reappeared since then. It's been about two weeks.

The transmission is a DRV (Dynamic Ride Valve) unit from a 4motion system.

I need to deliver the measurement data this afternoon.

Are there any other tests that can be done?

BTW: Is there anywhere a more detailed description of the measurement blocks and the basic settings/adaptation values? With VAG-COM, you really have to know exactly where to look.

So, measurement group 2 / value 4 shows = 81.9.

Probably the coolant temperature?

Hello,

The coolant sensor still seems to be in good condition based on the reading.
Other possibilities (for condition 12) include:

- Issues with communication between the engine control unit (ECU) and the instrument cluster.
- Error in the instrument cluster.
- Error in the outdoor temperature sensor (e.g., displays negative values).

Does the circuit breaker panel also have no error entries?

Hi,

Hmmm, I suspect that some control unit isn't properly coded for the climate control system. Could someone check the coding of the engine control unit (ECU), as that's the most likely culprit?

Did the car that the engine originally came from also have air conditioning?
Communication errors should be logged in an error memory within the model.

As far as I know, the other car also had excellent air conditioning, but I wouldn't vouch for that.

Other relevant errors are not stored. In any case, the instrument cluster has not stored any.
No communication errors reported.

He's complaining about the Airback, but that's okay because one is still missing.

I know that remote diagnosis is always quite difficult, but what else can I do? Where does the (VAG-COM) outside temperature reading come from? I could check that.

I don't have the exact data in front of me right now, but one of the initial readings from the engine control unit (ECU) was labeled something like '..Idle..' and it had a negative value with the unit 'cF'. I don't think it's related to that, right? I think it's probably something related to the idle speed.

Is it possible to re-code the STGs (Standard Terminology Groups)? Which ones would be suitable for this, and what codes would be used?

I probably know that I'm asking you a lot of questions here.

Hello,

What is displayed in measurement block 6 of the climate control system?

Measurement block 6:

19, 18, 18, 0

The first three are probably outside/inside/intake temperature sensors, right?
It seems to be okay.

Perhaps it would make sense to deregister and then register the Climatronic system again using the engine control unit (ECU). If I knew how to do it, I would have already done it.

Again: What else can I do now? (login codes?)

Or am I left with no other option than to go to the 'Friendly' (presumably a place or service)?

I've done a little more measuring... I'm slowly starting to understand what's going on... but I still need your help. Here's what I've found out:

Since the shutdown condition 12 comes directly from the engine control unit (ECU):

According to the wiring diagram, there are two wires connecting the M-STG (presumably a module) and the Climatronic (climate control system).

1) I have located the two pipelines (gn=T16b/2 and bl/ro=T12/3) between the Climatr unit and the M-STG.

2) The blue/red wire appears to be an OUTPUT from the climate control unit: (We disconnected the cable and then tested it).
- If the climate control system runs on 12V.
- If Klime is standing, the voltage is 0V.

Now things are getting complicated.
3) The control line (which in some models also goes to the automatic transmission) seems to be an INPUT to the climate control system.
- If the climate control is off, the motor is running = 0V.
...Until now, I haven't been able to start the air conditioning in my car...
Okay, so I bypassed it, unplugged the cables, and took measurements.
- The pulled-out cable is showing 0V, while the contact at point C is now showing approximately 12V. This means that the M-module cannot now bring the 12V potential at that pin down to 0V!
- Now I can start the Climatr., the vacuum coupling is engaged. I didn't have VAG-COM connected, but I guess the message 'Engine control unit intervention = Shutdown 12' was no longer present.
- The potential on the (aforementioned) black/red cable is 12V (feedback to the MTG, indicating whether the climate control is running? Speed adjustment?).

So far, so good, but now comes the crucial part:
IHR DENKT DOCH AUCH: Wenn ich jetzt das Grüne Kabel auf die Climatr. auflege, wird sie dadurch gesperrt und schaltet den Kompressor wieder aus?!?! OR?!?
NO, because the climate control system has started up, the green cable suddenly no longer shows 0V, but something around 10V (an open input), which means...
- Now I can reconnect the green cable, the compressor is still running... everything's fine.
- Apparently, the 'M-Regulation' regarding climate now prohibits it from running.
- But if I then turn off the climate control, the M-STG resets that cable to 0V.
- Consequently, I can't start the Clima (I'm back to square one).

CONCLUSION:
- Either there's a real wiring issue, I'll keep checking... (but we didn't take the wiring harness apart).
- Or the M-System blocks the climate control for a valid reason. Strangely, once it has been started, the M-System apparently sees no further reason to block it.
- The clutch and magnetic coupling appear to be functioning correctly.
- The reason seems to be this input connected to the Climatronic system.

Crazy, right? Just to add, the fans and other components also start up normally, etc. But it's not a solution to disconnect the cable.

If you have any other ideas or suggestions for me, please let me know.