1983 240D - Can someone tell me what setting I have to put the dials, slide levers, etc.. in to be able to "activate" the air condition compressor. I have pretty much figured out which slide lever to move where to get air out of different vents but what turns on the compressor? It is getting time to get it going. What is the blue/white "rotary dial" above the a/c control console?
thanks

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Jim

Jim,

The a/c is controled by the blue and white rotary dial. The more blue, the colder the output. Remember to turn on the fan(blower). The heater knobs also need to be pointing to the blue arrows.

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1982 240D 313,000 (4 speed)
1984 300CD 172,483
1985 German Shepherd Dog -Lacey- R.I.P.11/04/05

Hood Stars, Wrist Crowns and Obsession Dobs

The AC in German cars of 20 years ago won't compare with what you're used to in "modern" vehicles. My AC largely consists of sound effects. But I gladly suffer this and bad cruise control in light of the car's many other virtues.

Thanks - I will eventually get around to getting it going.
JimB - I am quite familiar with the characteristics of these a/c systems. It works in the 300D. At least it will get cool enough to evaporate the sweat LOL.

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Jim

Make sure freon charge is adequate---low freon will prevent the compressor clutch from engaging.

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K. Weimer
300SD (1)
300D (5) [Plus 1 parts]
300SEL 4.5 (2)
280SE (4)
280 (2)
250 (1)
250SE (1)
240D (7) [Plus 1 parts]
220D (11) [Plus 3 parts]
200D (2) [Plus 1 parts]
180c (with sunroof)

1995 Nissan UD1800 rollback
"If I can't fix it, it don't get fixed"

Jim:

The 240 AC works like my old 220D -- the dial (a twist knob on the 220) has a vacuum switch in it that changes the airflow to AC mode. There is a temp switch with a thermobulb in the evaporator that controls the temp, just like the old style add-on AC units one used to see, or the old Chysler cycling AC units.

Just bump the dial down -- you should hear the vac servos operate to change the air flow and the compressor should come on, along with the aux fan (make sure it works, too -- you can blow an AC hose otherwise, I did!). If the air doesn't start blowing out of the center vent, only defrost or heat, look for a leaking vaccuum line (green).

Low charge will open the low pressure switch and the compressore will not operate. Ditto for blown fuses, or corrosion.

The further you rotate the dial, the colder the evaporator (and the car) gets. Working properly, you will be frozen out -- the 220 gets icy if the knob gets turned too far!

You can switch it over to 134a by adding a couple ounces of ester base oil and charging to 85% of the rated R12 charge, no more. Works fine on the 220D as long as I don't need to accelerate!

Expect a BIG hit on performance at low speed with the compressor on -- Hans hooked up a relay on his to cut the compressor at full throttle -- you may want to consider this for interstate ramps. Otherwise, be patient, the compressor will cut out sooner or later and you can speed up then!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!