1974 240D Help with A/C - Mercedes-Benz Forum

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post #1 of 3 (permalink) Old 04-27-2009, 02:27 PM Thread Starter
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1974 240D Help with A/C


I am trying to get the A/C to work on this vehicle and am not entirely sure where to start.

Here are the things that I know:

Green light does not come on (I am assuming this indicates that the compressor is engaged/disengaged)

Compressor does not engage

System holds pressure

Blower and Blower switches work

So, what I would like to do FIRST is to get the compressor to engage. So I can get the system converted to R-134a.

I don't have any schematics of this system so I could really use a little guidance.

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post #2 of 3 (permalink) Old 04-30-2009, 11:38 AM Thread Starter
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Does no one have ANY information on this system?

I would really like to get the A/C in this car working.
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post #3 of 3 (permalink) Old 05-02-2009, 06:36 PM
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your car has 2 blower motors-one for the heat ,located behind the glovebox,and one under the radio,in the console (the grills on each side are the intakes) There is a change-over switch on the left side of the console, above the accelerator pedal,that is operated by vacuum.There is probably a leak in the system.Turn on the ignition and blower switch,if the heater blower is running,reach up by the pedal and actuate the lever on the change-over switch and hold it.If the heater blower turns off and the console blower comes on (the green light and compressor ,too,if the system has enough refrigerant)then you aren't getting the change-over.If you are careful,you can unplug the switch and jump the wires (I don't remember which-it's been years since I did it)to bypass it.Hope this helps.Be sure you clean all the fuses first-not just check-because a little corrosion will stop it. I think there is a small fuse box (2 fuses)on the firewall for the compressor and fan,check the manual if you have one.hope this helps.
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