Hi Guys,
I've been following the AC threads carefully and I still have a few question regarding my retrofit (R12 to R-134a). I am planning on removing my compressor and adding PAG oil, turning the compressor several times to flush out the oil mineral oil. Now for my silly question. Should I add the new oil directly to the compressor or should I install the compressor and then pull a vacuum first? If I add oil and then pull a vacuum, will not the vacuum suck up the oil? I see that they sell oil cans with the threaded tops for using the hose fittings to add the oil into the system. Is it better to pull a vacuum first and then add the oil to the system using the hoses? Should this be added on the low pressure side? Should I use the entire 8oz of oil? Thanks, I know that was alot of question.

Rene

I'm not a total expert on a/c systems, but have done a lot of work on my own. I would pull a vacuum & add the required amount with a charge before running the system. I've found some small cans with 2 oz. of oil & 1 oz. of R134 if you're using the do it yourself needle valve kit. Paul.

1984 300CD Signal Red

Very important! Always add on the low side when the system is running! The high side can cause overpressurization of the can, & adding into the low side while running will get most of the charge out of the can if using the small 13 oz cans. Also put the can in warm water to raise the can's pressure & get the most out of it.

If I undersand this correctly, the recommendation thus far is to add the oil when the system is running. Should I then first add the R-134a first and then the oil. Or should I turn on the compressor, add the oil and then the refrigerant?

thanks.
rene

Or you could use R12, which would avoid putting PAG oil in your system. In the end, your system will work better, last longer and you will save money.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

And you are going through with a R-134 conversion anyway? Not good!!!

The oil does not come out when pulling a vacuum.

It's easier and cheaper to add the oil before closing up the system. You can put the oil anywhere you want - it immediately begins circulating with the refrigerant, so it doesn't matter where you put it. For example, on a 124 chassis MB the low side has a threaded connection right at the forward firewall. It's very convenient to undo this connection, pour 8 ounces of oil into the low side, and then button it back up. Just make sure to spin the compressor by hand before charging and starting it up. You want the compressor lubricated, but you don't want it pumping oil!

- JimY

. . I'm no A/C expert and to see that, read MENU#16 and see what happened to my "perfectly-good" compressor doing what I did.

But for you, there's many people that would say . . why are you doing the conversion?? Check some of the A/C threads, and I believe that you'll see where R12 and R134 are fast approaching each other in cost b/c R134 is rising as fast as gas prices in So Cal ($3/gal).

Since your system was designed for R12, there are many that would tell you it won't work as well. So as the others have said... don't do it. If it's working ok, why fix it ???

What I learned from MENU#!7, was to do what's needed to be done (in my case all I needed to do was add a can of R134a, period), and try not to re-invent the wheel. You can't improve upon its design.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Ok, it seems like R12 would be the best choice of refrigerant to use but I was going to use R134a because it is widely available. I live if California, can I buy R12 and us it in a California car? Were can I buy R12?

Thanks.
rene

The vacuum removes moisture but I doubt it will remove oil from the compressor. The location of the low and high pressure taps are far upsteam and downstream of the compressor and I doubt even a powerful vacuum would pull the oil out of the compressor if you put it there.

Whenever I recharge an R12 system to R134, I always take the compressor off and flush it. Then I just take a funnel, and put 6 oz of ester oil in the compressor..and then spin the compressor over a few times to make sure it lubes up the seals and rotating items.