AC not turning on in '74 240D - Mercedes-Benz Forum

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post #1 of 3 (permalink) Old 07-23-2012, 07:54 AM Thread Starter
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Date registered: May 2012
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AC not turning on in '74 240D

In my '74 240d, I (I = experienced MB diesel guy) just replaced the guts of my AC system. Brand new ACcompressor, AC clutch, AC expansion valve, AC drier/accummulator, and new refringerant.

Once all the above parts were replace, mechanic tried to turn on the AC inside the car, but AC wouldn't start. The green light didn't go on.

Any idea what could be wrong, or what would be the recommended way to diagnose this issue?
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post #2 of 3 (permalink) Old 07-23-2012, 01:22 PM
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Date registered: Feb 2011
Vehicle: 1973 220D
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Vacuum leak? As I recall the switch operates the vacuum doors under the dash the one on the drivers side also pushes a switch which is how the green light turns on. Maybe that or a fuse but without the light the compressor will not engage.

Was the motor running when you tried? You might not have a serious leak just no vacuum left after sitting for a while.

Good luck, lots of hot days coming

Frank Flynn. Poet, Artist & Mystic
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post #3 of 3 (permalink) Old 07-25-2012, 09:59 PM
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Also, pressure switch bad? Jumper it to test.

And I believe there is a relay that activates the compressor clutch.

Chuck Taylor
Falls Church VA
1998 SL500
1959 220S
1970 280SL

Last edited by ctaylor738; 07-25-2012 at 10:01 PM.
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