Air Conditioning Noise

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Hawkwind

Active Member
Joined
Oct 2, 2013
Messages
491
Location
Brighton
Car
CLK 320
Hi everybody, need some advice with my problem.

Car is a 1999 CLK320 W208 70,000 miles

Yesterday I stopped on the way home to put the top down and noticed a noise from the engine bay.

Raised the hood and had a listen and thought it was probably the cooling fan hitting the plastic shroud.

I had already, by pure coincidence ordered a new V-belt tensioner and idler pulley, which I fitted when I got home. While I was there I had a look to see if I could see the cooling fan fouling the plastic shroud, but couldn't find anything wrong, or re-create the noise from earlier.

I did however notice that the fan would operate as soon as the engine was started. I'm assuming that this happens because the air-con is in operation? Is this normal?

Today I drove a short distance and the noise started again. I stopped and found the noise seemed to be coming from low down in the front/right hand side part of the engine where the air-con compressor is. If I revved the engine, the noise would happen on the over-run. As a test I pressed the ECON button on the climate control panel and the noise stopped, even when the engine was revved.

So it looks to me as though the compressor is the top suspect. Though otherwise the A/C works perfectly and blows nice and cold. No warning messages on the dash at all.

So some questions.

1. Is it safe to drive the car with the air-con in economy mode? I don't want anything to seize and ruin my engine.

2. Does anyone know the part number for the compressor and are they common across all models, or does each model have a specific type of compressor?

3. Is it worth buying a used compressor, or will they all be trash?

4. Has anyone else encountered this problem and would like to share? :)

Thanks in advance for any help/advice :)
 
I can only answer question 1. It is indeed safe to drive the car in economy mode.
 
I can only answer question 1. It is indeed safe to drive the car in economy mode.

I was wondering about the likelihood of the compressor seizing up and causing mechanical mayhem :(

Not had the problem but it could well be the A/C compressor clutch on the way out.

Is the compressor-clutch a separate part from the compressor, or is it all one unit?
 
The compressor is only driven when AC is selected. In economy mode the electromagnetic clutch disengages it, but the input side of said clutch continues to be driven by the serpentine belt.

The clutch is available separately.
 
Not saying your problem but i have the same and it has done it for 4 yrs without getting worse!
You will find if you keep the bonnet up for long enough for the a/c to cycle you will hear the noise stop and start......it is merely the clutch working
 
Thanks for the reply Keith.

I'll be keeping an eye on it.
 
Probably the clutch bearing. It's probably available on its own but I'd check the price of a new compressor also as parts tend to cost about the same. You'll waste a charge but the job becomes easier which should mean less labor cost and you'll have a brand new compressor.
 
So today I had some time to spend investigating.

I thought I'd slip off the serpentine belt and see if there was any play or roughness in the compressor pulley.

When I turned it by hand it seemed to be very smooth and easy to turn, with no discernible play in the bearing.

But still when I switch the A/C from econ to normal there is the clattering noise. It seems now to have a more
metallic sound.

Anyone done this job before and have some tips/experience? Seems like a simple enough job, just need to get the A/C system emptied.
 
Not saying its the same thing, but friend of mine had a similar noisy compressor, on a volvo, seems all it needed was a re-gas, as this helps keeps the compressor cool. so maybe when your on eco its ok, but possibly overheats on normal.
 
Not saying its the same thing, but friend of mine had a similar noisy compressor, on a volvo, seems all it needed was a re-gas, as this helps keeps the compressor cool. so maybe when your on eco its ok, but possibly overheats on normal.

Thanks for the replies guys.

You might be right Delderek, there's a mobile guy I used a year or two ago, really knew his stuff.

I think I'll give him a call and see what he thinks.
 
It will be the bearing (I’ve had this exact problem before), you can buy the whole pulley assembley for around £50 on eBay, a simple job.
 

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