sasmith

I get an intermittent screech at idle when the A/C is on. Never any time else. Is this the compressor, tensioner, A/C clutch?

Audio file:
http://www.stilife.com/screech.m4a

The screech is at the very end.

Any input is much appreciated before I get flocked at the dealership.

Thanks

S.

Glyn M Ruck

Most unpleasant. It's too metallic to be the Poly V belt. It is either the belt tensioner taking strain or you have a compressor or pulley on the way out.

There is no A/C clutch. Benz use a swash plate compressor that runs all the time.

From info provided this is as close as you are going to get. Further narrowing of diagnosis can be achieved with a 6 buck engine stethoscope or by listening with a long screw driver - be careful & don't get either into belt or rotating parts.

seagel1000

I have the same exact problem on mines. I posted the same question (what it can possibly be, never did a clear answer). Only happens when the A/C is on and is at idle. Does fine when driving at low or high speeds. ONLY at idle. Mine will dip or rise above 600RPM while the A/C is on. Which leads me to believe is why i have that rough-ish idle issue when the car is cold. After 15-20 mins, the idle stabilizes.

Help? lol

seagel1000

Here are the threads related to the issue. Maybe it can be of some assistance for you:

https://mbworld.org/forums/c-class-w...ble-issue.html (newest thread, this time it's always happening)

https://mbworld.org/forums/c-class-w...ring-idle.html (oldest thread, this one is intermittent like yours as well)

https://mbworld.org/forums/c-class-w...y-when-ac.html (2nd oldest thread, this one is intermittent)

sasmith

Thanks Guys,

I'm taking the car into the shop on Tuesday. I'll let you know what they come up with.

Stay tuned.

S.

slammer111

^ For the first 19s I thought I was retarded or something. :rofl: I was thinking "what screech?" You might want to shorten that sound clip.

That does not sound good at all. Let us know how it goes.

sasmith

Took the car to the doctor today. IIRC they say it's a idle tensioner and a tensioner. The compressor is fine. With parts, total bill is just north of $600.00. Parts will be in tomorrow and fixed as well.

Do they have to take the belt completely off to replace the parts? They said the belt looks great. Should I have the belt replaced anyway?

Thanks for the replies.

S.

Glyn M Ruck

Keep the belt if it's OK. It is not a big problem to change when it finally wears out.

sasmith

Got the car fixed today.
It needed a pulley #2712060019 $34.50, a tensioner #2712000270 $138.70 and $455.49 in labor.

The car makes no noise and drives great.

Thanks for the help!

S.

AdidasC230

glad to see you found a fix and it worked out well, congrats

Glyn M Ruck

Thank you for posting a sound clip. It makes diagnosis a lot easier!

Errr - sometimes

seagel1000

sasmith,

Thanks for the provided info man, I will try replacing these items!

-Chris

DanielFD

same story with me.. replaced the belt tensioner. all good but all it costed me is 60$ for the part and 60$ labor

derecklouthood

Is it possible to just change the alternator pulley? I had mine replaced.. Just wanna see if that's even possible.. Man.. i'm looking at a 12 pack and some angry times

Same symptoms with Ac on... grinding sound.. from what i'm reading i'm gonna replace tens. pulley, idler, i wanna do the water pump pulley and alt pulley if possible.

Any fixes from individuals who had it done?

marandod

same with mine clk (W209) 200 kompressor!
then i need to change this tensioner 2712000270?

black_c230

had the AC compressor, belt tensioner, and idler pulley. still getting this screech. Please help!!

black_c230

all that replaced, driving me mad!!!

black_c230

Oh and it only happens when the AC is on.

marandod

i solve the problem!! i change idler pulley, belt tensioner, belt and alternator pulley, now car is perfect!
problem was caused by seizur of alternator pulley, then belt tensioner go broken and idler pulley was changed for good measure