I have a 1972 W115, (220D) with factory air that I'm looking to get functioning again. What is the R12 capacity for this system?

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That's a rare bird! Not sure of the answer to your question but R12 is not legal to be sold. Many will ask you to convert to R134 but there is another option: R24 gas. Rare to find but worth the effort!

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Do not change it to R134; it will not cool properly and you will be unhappy.
Freon is available on the internet. I have four cans for which I paid $25 each.

As I remember you should add the Freon by weight but a full charge takes approximately four pounds or four cans.

You might search this forum.

I was just looking at this in the manuals as I was thinking of reviving the '74's AC which worked when I bought the car in 2013. I had to remove the compressor bracket to replace the thermostat housing gasket and I didn't bother with putting the system back together until recently.

The printed manuals I have, printed in the '60s and '70s, don't mention total refrigerant capacity of the system, only the oil (0.3 liters). What the book does say is to put enough refrigerant in to activate the pressure switch and then fill from there while watching for bubbles at the sight glass on the drier. Maybe newer sources indicate total capacity.

From memory, it's about 2lbs but there should be a sticker under the hood that will tell you exactly how much.

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With best regards

Al

It is legal with the right training and license.

What does the underhood sticker, or the FSM say?

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

First , use 134 a , inexpensive and work well , so start with 2 cans , that should be enough . Me , i would not use a/c on a 220d , too power robbing on the engine . Drove a 220 d for over 30 yrs . This system has a sight glass , so you can see .Dont overcharge , keep it on the low side .

Do not use R134; it will not give you enough cooling.

You might research R134 on this forum for backup.

The OP is in America where you can still buy R12. They outlawed it in the UK in the early 90's on account of how much bands like Kajagoogoo used in their hair.

FYI, RS24, also known as R426a is 93% R134a + some additives like butane to help carry the old R12 mineral oil. It's better to flush out the system, use the correct oil and go with a standard refrigerant that's readily available.

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With best regards

Al

Yep, that's a nope to the r134a in this system. I daily drove a w115 '76 240D which had a basic r134a conversion and it was never cold enough, like not even close. And I am not sure if this was due to the r134a, but I recall the rubber belt to the York compressor needing to be "bow string" tight. Otherwise, it would just slip. The York does rob noticeable power from the engine and was very noisy and had a lot of unpleasant vibrations to it.

I added 2, (12 oz) cans of R12 and it was blowing very cold. I didn't want to overfill. Maybe it will take a third can. I'll see how it cools when it is very warm but at this point, I'm happy.