Hi, this past week, my '89 190E 2.6 has been having AC difficulties. One day, I started the car, the air was on and all was fine. Drove across town and back, no problems. The car sat for about an hour, restarted and drove...no AC. Came home and popped the hood, compressor was not running. Waited about 2 hours, restarted the car, AC working fine. yesterday, same thing...I stuck my gauge to it and it has the correct amount of 134a in it...the electric fans work...the blower works fine.
Last night, I was driving around just listening to it...when I turn on the air, it's cold for a minute, then i hear a "bark" sound and it kicks out. Stop the engine and restart several times and it does this several times...all with the same bark sound...is my compressor trying to lock up?

From what you describe sounds like it mite be the clutch.

How difficult and how expensive is a clutch??? i'll try anything once
I usually do my own work.
thanks
greg

Don't replace the clutch on my guess that would be foolish without further checking it out. Go here http://www.aircondition.com/ and you should be able to find some qualified help.
Good luck
Rdanz

with the car being 15 years old I'd about rather replace the compressor anyway if that is the problem. I went to the AC forum and posted...we'll see what happens

Replace the belt and tensioner -- cheaper than a new compressor!

There is a speed sensor on the compressor, and it if slows down, the Klima relay will drop it off and leave it off until the engine is restarted. This is to protect the belt since there is only one, and you will get severe engine overheat without a fan belt.

I would also check the fuse for the aux fan -- if bad, the high side pressure can go pretty high, cause the belt to slip, and shut the compressor off.

Sadly, it could also be a compressor on the way out.

Could also be what happened to the "spare" I'm working on -- front seal leak caused the rubber in the clutch to fail, so compressor won't turn properly. That would account for the "bark", too. Won't last long, the rubber shreds.

I'd check the belt first, since that is more likely to be the problem than anything else. A dead belt tensioner will let you run so long as it's fairly cool, but let the belt slip as it heats up.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I'll second the belt as the problem. I also have seen oil leaks in the area of the clutch cause enough slippage to trigger the safety cut-out feature. A little brake clean spray into the clutch while off can solve that problem temporarily.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I don't think it's the belt...the compressor stops completely. The forum
airconditon.com sent me this reply:

"
Subject: Re: AC acting up
Date: September 11, 2004 at 19:20:37
Posted by: DNT on via: or 205.188.116.68
In Reply to: The message posted by Greg Crabb on September 11, 2004 at 18:57:55:

High side restriction causing compressor to kick out on high pressure most likely. This can be verified with a set of manifold guages to check the high side pressure when your compressor kicks on, you will see it run up sky high untill the limit is hit (probably around 400 psig) and pressure switch shuts the system down before it blows itself up! System will have to be flushed and new receiver/dryer and new expansion valve installed. Whomever did your conversion left some debris in the system or they failed to install a new receiver /dryer and dessicant bag has burst. How long ago was the conversion done (I bet it was recent) and do you know exactly what parts were changed out when your conversion was done Compressor?/Was the system flushed?/ Was a new receiver dryer added?/Was a new expansion valve added?/ What type and quantity of oil used?. The pressures must be checked to determine your problem, it sounds like restriction but only a guess without pressure readings. If you feel that the shop that did your conversion are competent, just run it back by it should only take them a few minutes to check it out. Good Luck"

I'll get the belt first though since it's cheaper than a compressor. Everything else works, aux cooling fans, blower, etc.

btw...the "bark" comes AFTER the compressor stops...no noise before...I can hear the engine strain just before the bark occurs.

This is your problem. replace your belt....I had the same issue and the belt would "occasionally" slip. This causes the speed sensor to shut the compressor off. This feature is to keep a "locked up" compressor from burning up the serpentine belt and leaving you stranded.

HOWEVER...if you compressor is going bad and on the verge of locking up this will also trigger the speed sensor and the compressor will be shut off. Check the belt first before you spend $$$$$$$

the compressor won't come on now...as soon as the button is pushed, it makes a loud groan sound and kicks out...before it would come on and cool for about 10 secs. I may be wrong but I think it's locked up now...I'll get to the belt first though. It all started so suddenly...working fine one minute and making noises the next, then kicked out.