my mechanic is working on my a/c and there is a possibility that the a/c evaporator is out. He is an awesome mechanic very good customer service. I was wondering is this common or very rare. Has anyone had this go out on them?

124's seem to have trouble with them, but I didn't think it was a common 123 complaint.

For my W210, there is a tool available to test the evaporator for leaks without removal. It bolts in place of the expansion valve to allow charging with high-pressure nitrogen. If such a tool is not available for the 123, you could make one out of an old expansion valve.

anybody

I have a leaking evaporator, it is somewhat common. What isn't as common is the cost of replacing one. The dash, center column, heater core and everything south of the firewall has to come off. Many old clips, vacuum actuators, plastic tabs WILL break. There are a list of service items on this web site that should be done if you are doing the evaporator. I don't know where the link is, but search for evaporator, and there will be a link to a photo step-by-step DIY. My mechanic demured on the repair, saying if he did it, it would cost $2k.

Hope that educates and pertrifies!

Couldn't you just add a tracer dye, set a pan under the evaporator drain, and check the water with a UV light to see if the evaporator is leaking?

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

You probably can't get a false positive this way, but the chance for a false negative is very high.

Pressure-testing the evaporator will tell you for sure if it is leaking.

It's common.

http://www.peachparts.com/Wikka/W123Evaporator

82 300TD and a 83 240D

While he's at it have him replace the vacuum elements.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car