Hey Guys,
I have a 83 300D. When I press the AC button on my temperature control unit it does not engage. I figure that it is because the AC freon is low and the low pressure switch does not allow the compressor clutch to engage. Does that sound correct? Now, I am thinking if I jumper the low pressure switch that it will allow the compressor to engage when I press the AC on switch. I want to try this to see if my compressor is working or not and that the problem is low freon. Is this a good way of trouble shooting why it is not working? Unfortunately I only have gages for R134 and not R12, which is what the car still has. I would like to make the change to R134 (I am in California) but would like to make sure all the components are functioning before I add freon.
Thanks.
rene :

rene,
Unless this is a euro model or a 240D, you should have an ACC system, as such there is no A/C switch. The center button on the ACC will allow the compressor to engage if called for by the system. The only sure way is to turn the temp wheel down to minimum. Anyway you can bypassed the low pressure compressor cut out at the Freon Receiver/Dryer. Its on top along with the Aux Fan High pressure switch. I think the Comp. cut out is the lower one. Just short the two contacts together MOMENTARLY with the engine running and the temp wheel at minimum. That should tell you if low freon is your problem. Typical leaks are found at the compressor, thermal expansion valve, and high pressure hoses. Converting to 134 requires high pressure hose, receiver/dryer, & possibly thermal expansion valve replacement. The system then needs to be thoroughly flushed and evacuated for the new Freon and oil. Search this site for additonal info. HTH

__________________
D. Blake
86 300SDL 340K (for sale)
83 300SD 205K (gone)
06 Chevy K3500 LBZ CCLB 50K
94 Chevy K2500 6.5L TD 250K (gone)

Are AC Delco compressors a direct replacement for an '82 D? I have found one on my car. The compressor will not engage with temp wheel to full cold. It spins freely when rotated by hand. I was hoping to cheap out on a factory AC Delco compressor as opposed to a benz compressor.

Shawn

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'82 300d
'73 Alfa GTV
'86 Porsche 951
'00 BMW 323 sportwagen

Are you sure you spun the compressor or just turned the pulley?
To turn the compressor you need a spanner wrench on the end bolts.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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Check this out

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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The Delco R4 is the compressor used for the 1980s 616s and 617s. Before that a York was used. I am not sure when they change over but I had a 78 240D with a York. Both 83s I have had have been Delcos.

__________________
D. Blake
86 300SDL 340K (for sale)
83 300SD 205K (gone)
06 Chevy K3500 LBZ CCLB 50K
94 Chevy K2500 6.5L TD 250K (gone)

HMM... Did I check it incorrectly? I was thinking that you cant turn the pulley because you would have to rotate the motor. With the engine off, I could rotate the center portion of the compressor with my hand freely, there was some resistance. I suppose I should bypass the low pressure switch and see if the clutch engages right? If it does... I probably have a leak somewhere which should be my next step.

danym...Those gauges look great. Looks like all I would need are the hoses that attach to the shrader valves.

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'82 300d
'73 Alfa GTV
'86 Porsche 951
'00 BMW 323 sportwagen

Hey,
$20 for a set of manifold gauges is awesome! If I didn't own a set already I would buy it myself. I didn't search for hoses but I can't imagine them being that hard to find.
With the engine running the compressor pulley will always be turning. Wether the compressor is on or not. To check it you need to spin the clutch. Use a spannerwrench, or any long wrench, and turn it using the bolts that stick out from the center of the pulley.
If it spins fairly easy then the compressor is more than likely in good shape. If it's disconnected you will hear a wet popping sound.
Jumping the pressure switch would work but I would get those gauges. They will tell you a lot more about what is going on.

I had a leak and finally found it at the expansion valve. removed the carpet under the stearing wheel and it's right up against the firewall. Look for oil that's a sure sign of a leak.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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I am still confused at how to turn on the a/c. I do not have a manual to check. On my temperature control unit there is a button that says "Auto" with a fan button and and a fan off button above and below this. I thought to turn on the a/c I had to press this Auto botton in? From this thread I am getting that you just have to turn the temperature wheel to the coldest position and the a/c will turn on? Can someone set me straight on how to turn the a/c on.
Thanks.
rene

http://skinnerbox.steaky.org/Service/W123/w123CD2/Program/Climate/83-600a.pdf

More info than you probably want...but then again knowledge is power!!

Be patient, site can be slow especially now with 10's of diesel folks now clicking on the link...

__________________
Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)

The high/low/auto button is only for fan speed.

Every button except the economy button will turn on the compressor.
It will stay on depending on the setting of the dial/thermostat and the cooling needs of the cooling coil.

Basically if you set the dial to lowest setting and press any button other than the economy one the compressor will come on.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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