Replaced leaking condencer to conpressor line. Evacuated system and added 2 cans of 134a. static pressure reading is 70 lbs.

Problem: the compressor will not operate - clutch doesn't engage; cooling fans don't turn on.

checked fuses and relay - all appear to be in good order.

Can the A/C switch in the dash be a problem - how do you check it ?

Any help is appreciated!

Have you tried putting power(12V) to the wire going to the compressor..??

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I will try applying power to the compressor to see whta it does.

However I took the ML in to see what the dealer would say - Dealer says compressor is bad and system is contaminated. Must flush the system and replace the compressor - cost $1900.

Just before I took the ML to the dealer I replaced the condenser to compressor hose - I saw no evidence of contamination from a failed compressor. Makes me think I'm not being told the truth. All oil that I've seen from the system is clear and yellow in color. When I turn the compressor by hand it turns smoothly.

If I opt for the dealer to fix the A/C is $1900 is reasonable price?

Is replacement of the compressor on the ML a difficult jobs?

You can do it your self. But first, you have to evacuate gas and oil from the system. You have to know oil amount, which will be evacuated and add same amount.
Replace A/C compressor and Receiver/Dryer with set of new O-Rings (don't forget to add new PAG-46 oil in it).
After that you can start make vacuum test and charge the system.
Another words it is not big deal, if you have tools, time and some experience.

Since my original posting I have had American Service Center, Arlington VA. look at my ML. They said the compressor was internally damage and contaiminated the system - need big time repair. $1900 estimate.

I had prior to that visit with ASC replaced the high pressure line between the compressor and condencer due to a leak at the pressure sensor. I also pulled a vaccum on the system and initiated a re-charge. However the compressor would not engage.

Did not let ASC do the repair, and while driving away the A/C began functioning ... cooling and the compressor was cycling. when I got home I finished charging the system and is functioning fine now.

I suspect I am a victim of the intermitant connection problem that I've seen mensioned in other questions on this forum. How do I find the connection that's at fault and what's the recommended fix?

Thanks for any help

Don't you just love it when a "professional" comes up with what appears to be "dead nuts" diagnosis, for big money of course, as this will cover ANY contingency. I commend you for having the guts (or lack of cash) to drive away from this diagnosis.

Jim in Phoenix

The "BAD" connection is MOST likely beneath the fuse box..where the wire from the compressor plugs into the fuse box...they get hot & create a bad connection...very common on the ML's

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I am also experiencing this problem. I saw ealier posts with photos identifying the suspected connector. I have taken out the connector board and looked at the bottom of the board where all the connectors plug to.

My questions is what is the specific recommended repair? Is the problem with the wire connection inside the connector? If so, what is the best method to fix this?
The connector by itself is not a replacement part I take it.