Climate compressor makes a grinding noise

Hello fellow DIY enthusiasts,

Since I'm a complete beginner when it comes to air conditioning systems (I've only been dealing with them for about 6 months), and I have a question about one, I went online to do some research and found this very informative forum.

This morning, my air conditioner is making a strange grinding noise, and according to what I can hear, the sound seems to be coming from the AC compressor.
The noise only occurs when the climate control is set to 'Auto' mode; it disappears in 'Eco' mode, and it's not related to the engine speed.

When the system is engaged and the car starts, the noise is present for about 30 seconds and then disappears. I suspect it's likely due to the compressor bearings, but could it also be caused by an insufficient refrigerant charge? Previously, it was that familiar 'AC whine,' but now it's being masked by this 'grinding' noise.

What are your experiences regarding the refilling of refrigerants?
I'm not entirely convinced about this Longlife oil from Volkswagen, especially after reading what people have said here.

Okay, I drive a Volkswagen Passat 3B, manufactured in 1998, with an AFN engine.

Thank you for your support.


Markus.

Hello, I also have a Passat from March 1998 with an AFN engine.

Mine has now reached 135,000 kilometers, and I haven't had any problems with the air conditioning yet.

Hab' vorhin noch die Ausströmertemp. gemessen: 3°C bei 34°C Aussentemp. und Überlandfahrt. Also alles voll OK!!

A grinding noise coming from the compressor should, in my opinion, always be speed-dependent (since the compressor is driven by a ribbed belt). It might also be the fan that turns on when the air conditioning is running.

As long as the cooling performance is adequate, I wouldn't recommend getting an AC service done; it's just a way for them to rip you off. If there's too little refrigerant, the system will shut down due to a pressure switch. If there's only a slight deficiency, the cooling performance will simply decrease.

Every air conditioning system loses some refrigerant. Some lose more than others. In my last Passat 35i, I didn't have to add refrigerant until after 7 years (approximately 230,000 km).

But I know that opinions are VERY divided on this topic!

Hello Delta Force,

Normally, an air conditioner only makes noise when it's turned on if there is too much refrigerant or cold oil present (refrigerant surge or oil slugging).
But that can be ruled out in your case, right?
Have you taken a closer look at the compressor, or have you noticed any oil leaks?
What happens if you turn on the air conditioner, switch it to "eco" mode after a while, and then switch it back to "auto" mode? Does that grinding noise reappear?

@KombiBlue

Quote:

If there is far too little coolant, the system will be shut down by a pressure switch; if only a small amount is missing, then the cooling performance decreases.

Unfortunately, that's not entirely correct. In the case of a refrigerant shortage, the cooling performance is initially still acceptable. However, the compressor sustains damage in the process, eventually leading to complete failure.

@Michael II

I have a few more questions for you in my thread that unfortunately remain unanswered (including some about the climate).

Best regards, WarLord.

Hello KombiBlue and Michael II,

Thank you for your quick response; this is really great here.

@KombiBlue
Ah, so you also have a blue station wagon, do you? *g*
Okay, I've now driven 114 km, and I'm completely satisfied with the air conditioning.
(subjectively not yet measured)

To be honest, I can't imagine that there is suddenly too much refrigerant/oil in the system. Because that whistling sound definitely wasn't present in the past few weeks.

I can rule out the fan because it wasn't running when the system started.

@Michael II

As mentioned above, I can rule that out because it cannot be refilled.

'When I turn on the climate control after starting the car, I hear a noise. If I drive for a while and then switch to 'Econ' mode and back to 'Start', the compressor engages, and in my opinion, the noise either disappears or becomes extremely quiet.'


Thank you...


Markus.

Sure, here's the translation:

'PS: When I have the system refilled, isn't the refrigerant measured during the evacuation process? And the oil is in the compressor, right? Is it a) replaced when the compressor is changed? And b) is the amount of oil also measured?'

Hello Delta Force,

Unfortunately, most workshops understand "recharging" only as removing the old refrigerant and filling in the new one. In my experience, the refrigeration oil is never changed.

If you want to change the oil, the system must definitely be flushed afterwards (with compressed air and nitrogen). I would also definitely recommend replacing the filter dryer.

Hello and thank you for the quick information.

I read in this forum that you can drain the oil directly from the compressor without losing any refrigerant. When you write that the system needs to be cleaned afterwards, do you mean the entire system or just the compressor? Because it seems like the oil is separate from the refrigerant.

Why did you ask what would happen if I switch back from 'Eco' mode to regular driving mode after a while?

Hello.

Markus.

Hello,

Normally, the oil distributes itself within the refrigerant circuit as follows:

* Compressor: approximately 50%.
• Capacitor: approximately 10%.
* Suction hose: approximately 10%.
* Vaporizer: approximately 20%.
* Liquid reservoir: approximately 10%.

You cannot drain the cold oil without also draining the refrigerant. The cleaning refers to the entire system.

OK, thanks, I'll keep you updated...

Delta Force wrote:

@KombiBlue Ah, so you also have a blue station wagon, do you? *g*

How do you come up with that????

@KombiBlue
That was intuition...