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'92 400E
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87 Posts
Discussion Starter #1
I have a 92 400E with 126k miles. It is having some electrical problems and I am wondering if anyone can shed some light. First off, the car runs great, and I typically put 200-300 miles a week on it. However, the AC does not work. The blower was recently replaced, but only blows at one speed. There is plenty of heat, but no AC. Also, when I start the car, all of the idiot lights do not come on before I turn the car to start... only the SRS light. I do not know if these two issues are related.

I have brought the car into a very good mechanic in the area that specializes in M-Bs only. He hooked up the diagnostic tool and the car reads fine with no codes. However, when he checked manually, he told me that there was no electricity going to the AC system. The AC has some "freon" in the system, but it is low. I expected this since the car was sitting for several years when I bought it in December. I am scheduled to bring the car back to him next week for more diagnostics. He has a working '93 400E and plans to swap out some modules and the switch panel from the cabin to see if he can isolate the problem. I just want to do a little homework, so I can have a clue and not be sold the farm. I've only used this guy once and he seemed fair, but likes to use factory parts, which, on a car this old may not make sense. ($500fan clutch last week) Anyone who has any thoughts are welcome to comment and I really appreciate the time!

Thanks,

GlenInProv
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,759 Posts
Glen,

Your "single" speed HVAC blower problem lies with the fan speed regulator. It is shot, but hasn't failed complete yet. As for "no electrical" to the AC system... I believe you mean that the AC compressor will not engage. You state that you know the system is low on freon. Low freon will prevent the engagement of the compressor clutch. This is by design, to save the compressor from burning itself up. On the receiver/dryer, there are two switches. One is a high pressure switch, one is temp switch.

I'd suggest getting the system fully charged with freon before replacing a bunch of parts that most likely are not bad. An experienced mechanic should know these basic principles of AC systems, regardless of it being a Mercedes Benz or a Ford, Honda, Chevy..

Good Luck,

Jayare
 

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1991 300E 2.6, 1992 400E, 1995 E320 sedan (RIP), 2001 E55, 2009 SL550
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139 Posts
Check the wiring at the compressor power supply plug. My 400e had a loose connection at #1. Resoldered and it ran. Common problem apparently.
 

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'92 400E
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87 Posts
Discussion Starter #4
Thanks all. I'll put in the regulator and get the system charged with some dye and see what happens....

Glen
 

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22 Posts
did you find any solution to the dash (idiot) lights not functioning? I am experiencing a similar issue with a 92 400E, Other threads on W124's indicate it could be instrument cluster ground, ignition switch, or alternator. My alternator output volatege measured 13.85 at battery after 40 min trip, have not delved inito the other options yet.

BTW I also have a 92 400E parts car

paul
 

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94 E320-current, 94 E420, 65 220sb
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124 Posts
Overlooked issue

You might want to check the fuse. Although they may look good, the fuse ends get corroded. My AC died the other day and I pulled the fuse (even though it looked OK) and cleaned the fuse tips and it worked again. I wonder how many MBs get sold because of no AC and that fuse issue...
 
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