Hello everyone!!

Just a brief note to request some advice from you guys. Again, my w123 is giving me a hard time... You know how old cars are, they behave properly for some months. Suddenly they start messing around with you. Later they behave again.... Its like having another girlfriend....

Anyway, after having an awful new year (someone busted my windshield with a rock in the highway, massive oil leak in the steering box, minor brakes issue), my loved TAKA-TAKA (that's how I call my car because of the way it sounds) is still messing around with me....

Yesterday I noticed my A/C is not working so today I woke up early to have a look at it. Everything works when I turn the system on, except the compressor. I checked it, and its working properly if I connect it directly to the battery. For some reason the A/C control is not sending the signal to the compressor to start.

Any clue to find the reason of the failure? I have the euro style A/C, with knobs for the blower speed and the heating, and a wheel for the A/C temp.

Thanks!

I couldn't advise you until I find out if your AC system is fully charged with refrigerant! If it isn't, then the system pressure cutout switch is doing it's job and a recharge will fix this!

Are you keeping the model and year a secret for some reason ?
Are you using R12 or R134 or something else ?

You're right about that! I'll ask a friend to check that for me... Maybe its that.

The weird thing is that the A/C was working perfectly (ice cubes coming out the vents) on december 24, when I got my windshield busted. The day before yesterday I installed the new windshield and yesterday when I took the car out for a little commuting I noticed the A/C didn't work. Seems weird because a two week break is not such a long time to cause the leak....

Sorry for the model/year secret, I forgot to mention it...

It's a 1982 300D NA Euro, with a 4-speed manual.

I'm not sure if r-12 or r-134... I'll check and I let you know.

Thanks and drive safely!

If you have a leak it would be wrong to just fill it up and let it continue to leak...

I'll check the system this afternoon to see if there is gas in it.

In case the gas is ok and there are no leaks, can anyone provide me a wiring diagram for the A/C system please.

Thanks!

The topmost switch on your AC Receiver/Drier is the pressure switch...if you jump that and your compressor clutch engages....it is most probably a lack of refrigerant......disconnect your jumper, and leave one of the wires disconnected....until you get your system charged.....

I have my AC Compressor clutch disabled in this manner......so that it will not attempt to engage when the defroster is in use.....otherwise I use the "economy" mode on my Klima........

SB

also of note: I have shopped around the area for a good automotive AC shop (I sold all of my AC recovery equipment and tools/instruments some time back).....my local MB dealership will replace my compressor with one that I supply, along with the drier and expansion valve.....do the R1324A conversion....flush and purge the system for $60.00/hr or about $300-$350......if I supply all parts.....they will not be responsible for any labor warranty.......if they supply the parts and warranty the whole deal it will be around $1800.00.....

__________________

Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

We need to know more about what tools you have or don't...and if you have some experience with refrigerants, etc...

In other words, for a start, how are you going to determine if it has enough ' gas' in it ?

System fixed!!! I called a friend of mine who is a refrigeration technician and aked him for the pressure gauges he uses. I checked the system and there was gas in there, but too little. He came by and did a pressure test to find leaks, and guess what??

There was a tiny leak in the pressure cutout valve. Somehow the valve body cracked, making the leak. I was lucky that even though the valve body cracked, the low pressure sensing mechanism remained working to protect my compressor.

Thanks for all your help guys!! Happy driving!