AC Compressor Noise? Troubleshooting Guide.

Hi everyone,

I'm new to your lovely forum and I have a problem I need to address.

I've been having a small problem for some time now. After starting the engine, the air conditioning compressor turns on as it should. However, there's then a grinding/scraping noise (it's hard to describe, but it sounds awful) for about 7-8 seconds. If I start the engine and the A/C is in 'Eco' mode, there is no noise. If I then activate 'Auto' mode, the noise reappears. Also, if I turn the car off for about an hour, the noise occurs again when starting, but it's for a shorter duration (2-4 seconds).

Therefore, I am quite certain that it must have something to do with the air conditioning compressor. However, I am unclear about where the noises are supposed to be coming from, and why they only occur for the first approximately 8 seconds, and only after a more or less extended period of inactivity? Unfortunately, I am not very familiar with air conditioning systems either.

Does anyone have a similar problem or a solution? I would appreciate a few answers, as this is quite annoying.

Thank you very much, and best regards.
Mike.

Okay, if it only happens at the beginning, I'm inclined to think there's a problem with the coupling between the drive plate and the compressor itself.
Can you rule out a low fuel level? And if it does start, will it cool down sufficiently above +5°C?

Thank you for the quick response.

I need to check the refrigerant level. I can't say for sure if it's still cooling properly. There weren't enough opportunities to check that during the winter. Where can I check the refrigerant level? (It's embarrassing to admit, but as I said, I haven't had anything to do with the air conditioning system before.)

Okay, here are a few more details about my vehicle:

Audi A6 4B
1.9 TDI 110 hp (AVG)
Model 2000.

To be honest, I'm not even sure how to check the fluid level... but that's probably not embarrassing. I think the Bosch service center is a good place to go for that. But I'll check right away to see if there's a way to do it myself!

I have now managed to identify the cause of the creaking/grinding noise. I tried running a system diagnosis using VAG COM. And there it was: at the point 'Ventilation for cooling V7' (Radiation Fan V7), I could identify the noise. But, as mentioned before, it only occurs when the system is first turned on after being idle.

So far, so good. But why is the fan making these noises? Is it rusting and needs to be 'freed' by being worn in?

Can this part be easily replaced, or is it integrated into the compressor? Or are there perhaps any repair options available?

Hello, the fan should be located on the radiator, usually on the left side when you are facing it. You are right about what you suspect. The lubrication is missing, and in some cases, there is even some rust forming.
You can replace the fan yourself.

Hi,

Thank you, that really helps me. I had already resigned myself to having to buy a new compressor.

Do you absolutely have to replace the fan now, or would lubricating it a little bit be sufficient?

He just makes noises. You could try spraying some Caramba or something similar on the shaft occasionally.
You only need to replace the fan when it stops working or when it bothers you.

Okay, I'll spray some Caramba on the fan tomorrow. That should do the trick.

Once again, thank you to everyone who helped me.

Regards,
Mike.