Just had my '89 190E A/C converted and no cooling. The clutch engages for a few seconds, squealing the whole time, and then dis-engages, squealing stops. I'm far from an expert but it sounds like the compressor is developing too much head pressure. Could this be a clogged expansion valve? The mech (non MB) who did the conversion thinks it's electrical - I asked why and he had no real reason.

Any help is welcome!

If the belt is properly tight the only thing that will slip it is a froze compressor. If it hasn't locked then it is too full or too full of oil. Can the hub be turned by hand with the engine off?

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

THe hub turns very easily by hand (with engine off) & the belt tension is correct. History - The reason for the conversion was that the a/c had stopped working due to low Freon (aka the compressor would not engage) and the garage I normally go to no-longer stocks R12. They think I have a leak, but were unable to find it with a UV light. (I had the system charged two years ago and UV dye was added.) I decided to go to R134 because around here, the cost of R12 (if you can find it) has gone through the roof!

Thanks for the reply!

- Also, when the clutch engages, it does turn, only slower than the belt - the reason for the squeal.

The clutch should draw 3-4 amps. Does it? If the clutch is slipping the gap is too big or the magnetism too small. The standard 3-4ohm coil should pull 3-4 amps if properly attached to battery voltage.

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

I've currently given the car to an import mech. I will pass along your suggestion. (Normally I do my own work, but I don't have the knowledge or equipment for A/C systems.)

Would the conversion cause the compressor to be harder to turn? I'm wondering if the clutch electrical was weak to begin with, but strong enough for the original R12, has the conversion to R134a exploited this weakness?

Thanks again, I'll post when I have some results.

The only way to tell is to look at the pressures.

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

You may want to consider reducing the charge volume by at least 15% whenever converting to R-134. Some have adopted the mind set of up to 25% less, for our climate (No.California-SF Bay Area) personally I am more comfortable with 15%.

Well it looks like the compressor is DOA. I guess it will be a hot summer for me !!!

Thanks for the help !!!!

Good Luck

I'm currently looking for a replacement compressor (reman). The web-site catalogs I go to (including fast lane) ask, "To which engine range does the vehicle belong?" and then they list four numbers :
-10-032786
-12-032712
10-032787-
12-032713-

Where exactly is this number on the car?

You won't actually find those numbers on the car as they refer to the european VIN number. But they are easy to convert. The last 6 digits of your chassis number are the number after 10 or 12. In the euro format the 10 mean 1= left hand drive and 0 means manual trans, naturally the 12 means an automatic left hand drive.

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