Hello everyone...I have been slowly fixing things on my 1983 Mercedes 300d, and have now gotten around to the air conditioning. The indoor blower works fine..but the comp. and outdoor fan wouldn't run by turning on the a/c inside. Well after investigation, I found that the system had NO refrigerant in it what so ever..which made me happy, because I figured that there is a low pressure switch somewhere keeping the comp. from running. So I put some pressure on the system and quickly found a large leak. I've got it fixed and the system is presently under a deep vacuum. I have got the 8.5oz of polyol ester oil to put in...(and being a A/c tech.) I also have a 30lbs. drum of
R-134a. To sum this thread up, I need to find out what the factory charge of R-12 was . I know if I can find that out, I will take 80% of it and thats the 134a charge I will need to weigh in. Thanks a lot for any help. Travis

My factory sticker sticker shows 2.9 pounds of R-12.

My car was converted over by the PO a few years back. I just went through a compressor and dryer replacement due to front seal leak. Then had catastophic failure because some nimrod spliced the high pressure line that is under the car. I found a replacement line for $420 but found a local hose rebuilder and paid $20. It's been holding now for a month.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I certainly appreciate your help. I want to get this as exact as I can..so your sticker says 2.9 lbs right? It's not 2lbs 9oz? Since there are 16oz in a pound, 2.9lbs is basically 2lbs 14.5oz. So can you just specify that for me, and then I will get 80% of it..and I should be good to go. Thanks again! Travis

My underhood sticker says (for 123/126) 2.9 lbs. or 1.3 kg.; comes out to 46.4 oz.

I've always used this figure with consistant results.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

your an AC tec.. good.. now if the old system was R-12 you need to evac it and replace all the seals and oil... before puttint 134a in... and the manifold guages etc... im getting around to getn 609 certified and get the guages to do my system

Alright so its definitely 2.9 pounds. Sounds good, I am going to get it all charged up and ready to go, and I will post a reply to let you know how it goes. Yea, I am an A/c tech., but not for automobiles. My father has done Heating and Air his entire life (since 14 or 15yrs.old), and in the 80's he started his own business. As of today, it is just he and I and we do mainly residential..sales, service, new installation, ductwork (everything). So I have had NO experience with automobile a/c. But I decided last year to go to a tech. school and take ACR (Air conditioning and refrigeration). And before tackling this project, I talked to 2 of my instructors, and they gave good advice/directions. Like I said, I fixed a leak, pressure tested(it held), and now it is under a deep vacuum and has been sitting..as long as it is holding that vacuum today..I am good to go. I actually don't have a set of 134a gages, but as long as you have any set of refrigeration gages, you can get a pressure reading and take that to a PT (pressure/ temperature) chart, and get what you need. But I am going to use our electronic scale and weigh in 37oz.(R-134a) which is 80% of 46.4oz(R-12).Hey thanks again for your help, and I will be back later today to update..Travis