How much oil does a W124 ac system need? - PeachParts Mercedes-Benz Forum

jbach36 · #1 06-13-2017, 12:32 AM

I watched a VERY good video on YouTube about how to PROPERLY charge an a/c system, by "Chris Fix". I think after watching his video, that I can actually do this!

https://www.youtube.com/watch?v=Pdq8JAlct6s

Mind you he's charging up a Toyota truck. I don't know if the same rules apply to an older Mercedes.

One thing he was talking about was finding out how much oil your car's system needs. Where can I find that info? Also are there any other caveats that I need to know vs what was shown in that video?

1991 300d 211k

leathermang · #2 06-13-2017, 10:17 AM

IN GENERAL I like what he said about many things....

but a person needs to ask why they needed to replace their compressor in the first place.. there are reasons which would indicate some very important actions should be taken before worrying about the specific amount of oil needed in their system

If your compressor suffered a ' black death ' .. then it spread bad stuff into the system which needs to be physically removed .... or it will likely kill the replacement compressor very soon... and you will be back to square one AND with less money in your pocket...

On pulling 30 inches of Mercury when measuring the vacuum ... the amount which can be pulled is related to the barometric pressure at the time you are working.. 29.92 is the standard pressure on a standard temperature day at sea level... by definition.... so keep that in mind when pulling looking at the gauge.. almost certainly not going to be able to pull that much... so the critical thing to watch is MOVEMENT ... are you leaking air into the system after you have pulled whatever best vacuum you can pull ? People will argue with me .. but you need a two stage pump to do this work...

The amount of oil a system needs... for our old Mercedes Diesels... can be found in the Factory Shop Manual... BUT the only way to know how much is in there.. unfortunately... is to completely flush the system... then weigh in the correct amount...

There is an added problem with some of our Mercedes as they use a compressor without an oil sump... so all the lubrication it gets is from the oil being dissolved in the refrigerant which is circulating through the system...

I object to dye being added to the system. I think it has the potential for gumming up small things like the TXvalve.. AND more importantly will NOT help find a leak in the evaporator.... so I suggest the EPA approved method of a traceable gas being added to Nitrogen being used to find leaks.... all this is discussed in the AC thread...

My Signature has a url for the ' AC Thread' .. which is highly recommended reading...