seagel1000

Hey all!

it has been a while huh!

I'm having an issue (not frequent, but did happen about 5-6 times within 1 month).

On the hot days, i would turn on the A/C and usually, i dont turn off the A/C when im about to turn off the vehicle. Anyways, i was leaving Walmart and also a restaurant, when i turned on the car, the A/C was left on full blast and the car made a chirping/rattling noise coming from the engine bay. I was on Reverse because i was leaving quick and put it on Park thinking it was something else but the noise wasn't going away. I turned off the A/C immediately after wards and the sound went away like it never happened. Kind of sounded like a mini-rattle/ dry belt squeeky noise.

Any ideas what it might be. The sound hasn't occured since.

capt_paul

Same thing happened to my '05 C230. I believe it may be the tensioner starting to go. The belt appears tight though, so it may be something else. I just replaced my ac compressor about two months ago, which may have been caused by this problem.

Buellwinkle

Could be an idler pulley ready to go, could be the a/c compressor ready to go or low on coolant.

aecasasus

I agree with capt_paul and buellwinkle, it's either the tensioner or the compressor itself. Unfortunately, the only way to check it will be poping the hood open and pin-pointing the issue. Good Luck!

seagel1000

Thanks fellas. Hope all is good. I had the car checked out twice by my technicians thats been at Mercedes for 9 years and nothing seemed to be wrong with it. It was one of those "I just got my car" inspection and the other was for that work call re: the oil in cam sensor. Other than that, the A/C was recharged by them and checked and visually inspected and all was good?

Thanks anyways!

seagel1000

Hey all had to repush this back to date!

It is now happening pretty much any time i turn my AC on while driving short range (in the city). I turn on the vehicle, before hitting reverse or drive i turn on the AC, put it in either Reverse or Drive and it starts chirping and squeekin'! I notice the RPM don't go any lower than 600 when its on either of two gears (R or D). As soon as i turn off the AC, its like it never happened. Turn it back on and it starts the noise again. The noise is only there from 600-750 RPM, other than that, its cool if the car is running 800RPM +. Any ideas on what to do or check out?

I Appreciate any responses or suggestions!

Chris

LILBENZ230

You need to stop running the A/C and get this checked NOW. It is my understanding that the car will sacrifice the compressor ($1300 according to capt_paul) to make sure the car doesn't strand you. Once the A/C stops cooling, it's too late. Right now you may have time to get the problem fixed without having to replace the compressor.

How many miles do you have on it? I haven't had this happen to my car and I'm knocking on 60k. Hoping it doesn't happen.

dnlow

This may be totally off base but I will just throw it out there.

I had a similar issue where when I started the car and backed out of the garage there would be a chirpy, metal grinding sound and a very rough idle. I also felt it was AC compressor related because when I turned compressor off the idle speed would go up and the noise would go away. It also seemed to go away after I drove it a bit. Car was under warranty and the dealer replaced the alternator. Here is something that explains what had happened to the alternator:

Detailed Notes: The Valeo units have what is called a "floating stator", meaning that when the unit is assembled the rotor is not pressed into the alternator castings like a conventional alternator, but is placed/centered in the housing and held in place by the pressure of the through bolts holding the entire assembly together. If these units are dropped, or are subject to pressure during installation,the stator can actually shift slightly which will cause noises that range from a magnetic type 'hum' to a metal-on-metal noise

This is what happened to my alternator. After it was replaced the idle was fine and all the noises went away. Just thought every bit of info could help. Unfortunately, everything worked fine on my car before I took it in other than the noise. So I do not know how to determine how to tell if this is your issue. I guess the dealer had seen it before and they knew where to look.

I guess one way to tell is to remove the belt and see if the alternator pulley spins freely.

LILBENZ230

It seems like the guy on here scottisha (search his posts) has had an "alternator sprag bearing" fail about 3 times on his 2005 C230 (with 190k miles) and when it failed it ruined the A/C compressor. So you might be onto something there.

seagel1000

just hit 70,100K on the vehicle!

seagel1000

Should i get a video on here so you guys have a better idea of what it can be? I dont want to be left stranded or hit with high bill, i have enough going with my recent accident!



Chris

LILBENZ230

You can post a video if you'd like. I can't promise that not running the A/C will save anything, but it might, so I'd stop now. Search for "sprag bearing" on the forum and see what you find.