Broken AC Compressor Clutch for VW Golf iV TDI

Hello everyone,

I previously asked a question about an error with my Climatronic system, and now it's completely broken.
During a multi-hour drive, a sudden rattling or whirring sound started coming from the engine compartment (similar to the sound of something rubbing against a fan blade).
At the VW workshop, a broken compressor coupling was diagnosed.
First, the entire climate compressor needs to be replaced (the replacement part costs EUR 700!! - I live in Austria).
When I declined the immediate repair because I wanted to have the damage fixed at my workshop (approximately 350 km away), I was informed of the potential risk that the 'glass' could fall off and that I could therefore be stranded.
I decided to take the risk and pick up the car (a diagnosis couldn't be made immediately, so I didn't stay at the workshop).
When I arrived at the workshop, they were in the process of trying to attach the coupling of the replacement compressor to my compressor, but they were unsuccessful.
The statement was that it is almost impossible for the clutch to simply break on its own, and the assumption is that the compressor locked up, which caused the breakage.
Now, I'd like to ask you what your opinion/experience is on this topic.

- Is it possible for a warm compressor to suddenly become blocked after several hours, but still remain cold?
- Would it be worthwhile (if possible) to only replace the faulty clutch instead of the entire compressor?
- How can you determine if the compressor itself is damaged (specifically, assuming it only blocks after a prolonged period of operation)?
- When the compressor is replaced, what other work needs to be done around it (e.g., replacing the refrigerant, any hoses or belts, etc.)?
- What is your estimate of the expected costs?

My Golf iV Varant is a TDI 66kW AGR model, manufactured in 2000.

There are many questions, but I hope you can answer at least some of them.
Sure, here's the translation:

'Thank you in advance.'
H.

Well, the big question is, WHY did the clutch break?

The compressor shaft is mounted and lubricated with silicone oil, which is added to the refrigerant.
Okay, so... did you have the system filled with refrigerant since its installation date? Has it been operating without a charging port?

Were there any noises before?

Of course, I'm also wondering why it broke.
I had the air conditioning system serviced three months ago, including a complete recharge. What could the workshop have done wrong during that process?
The air conditioning system seemed to be cooling without drawing in any outside air. When the outside temperature was between 10 and 15 degrees Celsius, the temperature regulation didn't seem to be working properly (see my older thread - intermittent error with a faulty temperature control flap).
However, the current temperatures have hardly required the full cooling capacity to be used...
There were no suspicious noises. I took the car to the car owner's club for a diagnosis of the temperature control valve issue, and they roughly checked the function of the air conditioning system, but they also didn't detect any unusual noises.
In another forum, I read a post where someone also reported an air conditioning failure, which was preceded by a howling noise caused by a slipping clutch in the 1st to 3rd gear.
I experienced a similar noise in first gear when starting on inclines, especially when I engaged the clutch slowly.
However, I don't know if the noise came from the clutch or something else.

H.

I had the air conditioning system serviced three months ago, including a complete recharge. What could the workshop have done wrong during that process?


A lot and a little.

The system will be completely evacuated (this amount will be recorded), then the gas will be cleaned and prepared for refilling. The oil will be disposed of in a container. The technician only needs to connect two lines to the climate control unit for this purpose: the high-pressure line and the low-pressure line.

Okay, then he needs to check the exact specifications for your system and draw the appropriate amount of silicone oil into a large syringe. (For example: 850g of refrigerant for the G4 model, of which 150g is silicone oil).

This is then injected into the low-pressure section via an adapter.

Okay, so the technician calculates (850g - 150g = ?) and, using a simple rule of thumb, adds 700g of R134a. This can be read or adjusted on the machine.

Sources of error:
- Not enough/too much oil drawn up.
- Used oil (exposed to air).
- Too much/too little refrigerant added.
-Incorrect oil-to-refrigerant ratio.

Sure, here is the translation of the text from German to English:

'usw...' means 'etc.' or 'and so on.'

You should remove the compressor and check it to see if it still spins freely. This will quickly tell you whether it's seized or not.
But if the car was 'serviced' three months ago, I would almost suspect that as the cause, without wanting to blame the workshop.

Hello Julian,

If the technician calculates things the way you do, then it's likely to fail.

850g - 150g = 600g For me, that equals 700g, or did I misread something?

Regards,

SVEAGLE

- Is it possible for a warm compressor to suddenly become blocked after hours, while still being cold but not working?

'When the compressor is blocked, it usually leaves marks on the V-belt.'
It happens relatively often, but usually the timing belt is either 'burnt out' or completely missing.


- When the compressor is replaced, what other work needs to be done around it (e.g., replacing the refrigerant, any hoses or belts, ...).


To replace the compressor, the refrigerant must be evacuated.
This will be refilled later, but only the oil will be replaced.

850g - 150g = 600g , but for me, it results in 700g.


Hehe, complaining about others, then making the same mistake yourself. Of course, it should have been 700g... I've corrected it above.

Thanks everyone for your numerous responses.

Regarding the markings on the serpentine belt, I should add that the roadside assistance service I initially contacted first suspected a damaged serpentine belt tensioner, as the belt was uniformly darker and shinier on one side compared to the other.
It sounds like the compressor is blocked.
Well, I'll see how much this convenience will cost me.

H.

'My magnetic clutch broke in early summer 2004 (G4,00). The 'friendly' service technician at Bosch mentioned that VW probably had problems with this model year. They would 'stick.' Every week, someone would come to the workshop with around 100,000 km (62,000 miles) on the clock. Before 2000 and after, 'they would work fine.' He recommended installing a completely different compressor. The cost was 750 euros at Bosch. A new magnetic clutch from VW was 250 euros. I then replaced the magnetic clutch. The likely cause of the failure was repeatedly switching between 'Econ' and 'Auto' modes at high RPM on the highway. 'Auto' engages the clutch each time, which I unfortunately only realized later. When the compressor has to start against pressure, the magnetic clutch says, 'Thanks, that's it!' I then tried to soften the engagement process (using an NTC resistor). Also, I only allow the clutch to engage below 2000 RPM (using a speed monitoring system). Let's see how long this clutch lasts!'

Since Pedro dug up my old thread, I can briefly share the result.
I went to my trusted independent repair shop, hoping that they might have a different approach than the 'VW way.'
After inquiring with VW about the cost of a clutch and a compressor (220 and 700 EUR, if I remember correctly), they remembered an auto parts dealer from whom they had only received a catalog a few weeks prior.
Result: a new climate compressor for 460 EUR - including the VW/Audi emblem, so it's an original part!
Including the installation and another small item, the total cost came to approximately 560 EUR. That's why I wouldn't have even received a cleaned, used compressor from VW.
Since then, the Climatronic system has been working perfectly again.

Oh yeah - I always keep the air conditioning set to AUTO.

H.

Same situation, same price... It happened to me just like that, I drove away from the traffic light and suddenly there was that howling, rattling noise. It cost 1100 euros. A new A/C compressor with an electric coupling, a real show, I have to say.
'The Golf 4: once and never again. It's a nice car, but fundamentally flawed, especially the early models. Parts that shouldn't break keep breaking, like the wiper linkage, air conditioning compressor, window lifters, and rear wiper motor... *shakes head*... Best regards, Windl.'

@Julian

AFAIK, a significant amount of the oil remains in the compressor and other parts of the system and is not drained out. Simply refilling the coolant, plus the amount of oil that the device has separated, should be sufficient.

Best regards, WarLord.

@Julian

AFAIK, a significant amount of the oil remains in the compressor and other parts of the system and is not drained out. Simply refilling the coolant, plus the amount of oil that the device has separated, should be sufficient.

It was about the coolant fluid that the mechanic was supposed to refill.

Best regards, WarLord.

Yes, maybe, but I still don't understand the meaning of your post. Above, I described exactly how the filling/refilling process works.

'Kälteöl' doesn't exist; you probably meant silicone oil in this case.

It should actually state that the mechanic should only add the amount of oil that the device has separated out, because a significant portion remains in the air conditioning compressor and the other components.

Best regards, WarLord.