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Discussion Starter #1 (Edited)
The A/C on our 98 E320 no longer works (bad evaporator). But the compressor is of course still there. Today while driving, I noticed a lot of intermittent noise coming from under hood. When starting after a stop, no noise for about 5min. Then it would start and it would be intermittent and not in sync with engine rpms. When I got home I recorded it. Not to clear, but it is the noise above the normal engine noise:

(for some reason this link does not work in Chrome, but does in Firefox)

I thought it might be the idler/tensioner, but after listening with tube and then stethoscope, I am pretty sure noise is coming from the A/C compressor.

My question: Can I eliminate the compressor altogether?? I seem to recall that a shorter belt was available (Is that correct?). Without compressor, it would have to lead from the PS pulley to the main crank pulley without touching anything. In this diagram it looks like it should be OK, but it is just a diagram! Any one done this or can confirm it will work?

 

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You should be able to. Also you could remove the clutch plate (10 mm bolt in the hub), and check if the noise persists, and also remove the compressor electrical connection at the top of the compressor..
 

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Discussion Starter #3
You should be able to. Also you could remove the clutch plate (10 mm bolt in the hub), and check if the noise persists, and also remove the compressor electrical connection at the top of the compressor..
Just so I fully understand.
  • Is that 10mm bolt the one in center of clutch pressure plate (9 in diagram below)?
  • When I remove the bolt, does the pressure plate come off? Or does compressor just not get driven? Hopefully pulley doesn't fall off?
 

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  • Is that 10mm bolt the one in center of clutch pressure plate (9 in diagram below)?
    [*]When I remove the bolt, does the pressure plate come off? Or does compressor just not get driven? Hopefully pulley doesn't fall off?
1) Yes

2) When you remove the bolt the pressure plate will come off. With no pressure plate, The pulley will free-wheel, even if the controller tries to engage the clutch, as there is no pressure plate to engage. The pulley is not held by the 10 mm bolt. I believe there is a c-clip, and then lots of pulling to remove the pulley. When my compressor seized, I removed the plate to investigate and never put it back in place till I get to replace compressor.

I would try removing the connector first, and see if the noise goes away. If not, remove the pressure plate. If the noise still persists then it may be something to do with the pulley bearing (not knowing what the noise you hear is like).
 

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Discussion Starter #5
By the way, I found this on-line:

6. Install a shorter belt to bypass the compressor. Route belt as shown in Fig. 1.
• Engines M112/113 – 20 x 2315 to 2325 mm (P/N A011 997 96 92).
• Engines M272/273 – 20 x 2330 to 2340 mm (P/N A011 997 04 92).
 

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Discussion Starter #6 (Edited)
1) Yes

2) When you remove the bolt the pressure plate will come off. With no pressure plate, The pulley will free-wheel, even if the controller tries to engage the clutch, as there is no pressure plate to engage. The pulley is not held by the 10 mm bolt. I believe there is a c-clip, and then lots of pulling to remove the pulley. When my compressor seized, I removed the plate to investigate and never put it back in place till I get to replace compressor.

I would try removing the connector first, and see if the noise goes away. If not, remove the pressure plate. If the noise still persists then it may be something to do with the pulley bearing (not knowing what the noise you hear is like).
So it is OK to run without the bolt? Pulley just held on by circlip? I will try both, but seeing we will never spend the $4000+ for the Evaporator replacement, it might be just as well to remove the compressor. But if I don't have to, that would make things easier. Perhaps with the short belt, it can stay?
 

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You can of course invest in a shorter belt and it will work. But if you want to isolate the noise (I went back to the first post and noticed the video, thanks), you can first identify what the cause is. It appears that the controller is trying to engage the compressor (even though you do not any refrigerant in the system, due to some disabling feature (check of the refrigerant pressure sensor) the controller may not know that, and backs off. Why would the controller try to a/c even it is not activated ? for defogging.

As I said, the easiest way is to remove the compressor electrical connector which may be hard to reach, and pull. If you never will use it just cut the cable :).

I still have the old compressor. It has a big snap ring that needs to be removed to remove the pulley, plus a pulley removal tool. Putting back the 10 mm bolt will not hold anything.
 

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Discussion Starter #8
Thanks very much for that. Nothing like first hand experience!

I was not sure if I would find a short belt locally, so went ahead and ordered one on-line (Amazon.ca - C$35 free shipping! - here early next week) In the meantime, I will start with disconnecting the electrical cable. If that works, stop there! Next, I may remove the bolt and see what difference that makes. If tight, I may wait for belt :)

This is my wife's daily driver. I just finished annual rust spot touch ups and took it for a drive. That led to this thread ;)
 

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Discussion Starter #10 (Edited)
Yes, I did put dye in the refrigerant. Then took some digital pics (they show up the dye). I did a search! I recall posting here about the leak:


Some time later, I decided to try a leak stop sealant. It cured the problem. A/C was fantastic! But only lasted about a day or two before it blew again!
 

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Wow :) It was 7 years ago. Now, I guess everything else is dried up, and would require a major overhaul, even if you replaced the evap core. The only things that are worth salvaging are the aluminum+hose lines, They are pretty expensive "dealer only" parts.
 

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Discussion Starter #12
It's not going to happen! We don't need A/C. We have 4 cars, just one with A/C! This is Canada and small town.. Hot in summer, but my wife just drives this car to golf course and shops. Once in a while we go a bit further afield, and with sunroof open, it is no hotter than driving the SL top down :)
 

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Yeah, I know. I lived in Ottawa between 1980 and 1984, and never needed a/c. And those days a/c was a luxury option in big cars anyway :). Between my place and work was a quiet straight drive, so opening the windows was just fine.
 

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Discussion Starter #15
Do you get the noise even with the “EC” button on.
Yes, I think so. But today when I drove the car, as often happens, it didn't make the noise at all no matter which buttons I pushed. As a result, I am not going to do anything other than put on the shorter belt when it arrives. I think I have a spare long belt, so will leave A/C pulley & Comp in place and use the long belt as spare.
 

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Is it the cyclical grinding noise that's the problem? That sounds like my water pump when its pulley failed. It had slightly fallen off its axis, so the pump blade would scrape against the pump body once every revolution.
 

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Discussion Starter #18
Is it the cyclical grinding noise that's the problem? That sounds like my water pump when its pulley failed. It had slightly fallen off its axis, so the pump blade would scrape against the pump body once every revolution.
I found that the A/C pulley wobbled. I am in process of installing new shorter belt that bypasses the compressor that is no longer in use. At same time installing new tensioner and idler pulleys.
 

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Discussion Starter #19 (Edited)
By the way, I found this on-line:

6. Install a shorter belt to bypass the compressor. Route belt as shown in Fig. 1.
• Engines M112/113 – 20 x 2315 to 2325 mm (P/N A011 997 96 92).
• Engines M272/273 – 20 x 2330 to 2340 mm (P/N A011 997 04 92).
Ok, I finally got all the parts and got this done. New idler, new tensioner pulley and new 2325 belt.

It works, but there is, I think, a problem. The belt (1 in sketch) runs very close to the A/C compressor pulley. With engine off, I can spin the A/C pulley. I can get just single sheet of paper between belt and pulley. And when I run the engine, the A/C pulley spins. And, it is the flat side of the belt that faces the grooves in the A/C pulley.

If I run it like this, I am afraid the belt may get damaged. So next step would be to remove the A/C compressor or just the A/C pulley.

Just got done, so haven't looked into this yet.

Would it be possible to remove the pulley in place without taking out the compressor?
Seems like it - found this TSB (it doesn't apply to W210, but hopefully similar once clutch removed?
https://mbworld.org/forums/attachments/c-class-w203/413859d1506625280-ac-compressor-clutch-bearing-replacement-s-b-83.55_87f.pdf

Edited out other questions!
 

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Ok, I finally got all the parts and got this done. New idler, new tensioner pulley and new 2325 belt.

It works, but there is, I think, a problem. The belt (1 in sketch) runs very close to the A/C compressor pulley. With engine off, I can spin the A/C pulley. I can get just single sheet of paper between belt and pulley. And when I run the engine, the A/C pulley spins. And, it is the flat side of the belt that faces the grooves in the A/C pulley.

If I run it like this, I am afraid the belt may get damaged. So next step would be to remove the A/C compressor or just the A/C pulley.

Just got done, so haven't looked into this yet.

Would it be possible to remove the pulley in place without taking out the compressor?
Seems like it - found this TSB (it doesn't apply to W210, but hopefully similar once clutch removed?
https://mbworld.org/forums/attachments/c-class-w203/413859d1506625280-ac-compressor-clutch-bearing-replacement-s-b-83.55_87f.pdf

Edited out other questions!
I think the compressor in the link is different. It is what they call a clutchless compressor. Whenever the engine runs the compressor is engaged but free-wheels under the control of the Climate control unit (AAC) through the control valve.

I happen to have a picture of the compressor pulley picture with the clutch plate removed.

You can remove the circlip(s), but I believe you need a pulley puller, or brute force with a hammer from the back :).

To remove the compressor:
If you can get under the car with jack stands and additional protection, and remove the driver wheel, you should be able to remove it with E10 sockets if I remember. The tough part is to remove the a/c suction and pressure ports which are at top of the compressor (allen bit used with a long extension from the top).
 

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