1981 Mercedes 240D OM616 A/C Question PLEASE HELP! - PeachParts Mercedes-Benz Forum

marco5 · #1 07-22-2013, 02:44 PM

So I'm charging the completely empty system with R12 tomorrow. Can a professional please tell me the following?

1) How much R12 does the factory call for?

2) What is the capacity for mineral oil? Is it okay to add oil to the dryer also or is compressor and lines better?

3) Yes I have R12 and I've been told mineral oil is the best for this type of car. Is this true in your opinions?

Doktor Bert · #2 07-22-2013, 03:07 PM

R-12 capacity (with a York compressor) should be 2.5 lbs (40 oz) of R12. Mineral oil, often called '525' is the correct lubricant. Full system oil capacity varies depending on the documentation you read can be either 6 to 7.75 ounces is full system oil capacity if it is 100% oil free.

I would suggest you consult the W123 climate control manual for the specifics:

MERCEDES W123 Service Manual Climate

Also, there are some rules for the addition of oil to a system that still has some residual oil left in it.

Refer to attachment...

JHZR2 · #3 07-22-2013, 09:43 PM

Completely empty???

DO NOT charge an empty system as it has air and moisture in there.

Do you know why it leaked out? It is illegal to refill CFCs without tracking and repairing the leak. R-12 is selling at around $1000/30# wholesale from refrigeration supply do its still expensive.

Remember that air compresses different than refeigerant, and moisture turns to acids.

Do it right - replace the receiver dryer and any o rings you can, sealing them with nylog. Pull a vacuum to 50 micron. Pressurize with nitrogen, find leaks and fix. Re-test with nitrogen to verify, then pull a vacuum for as long as possible to 50 micron or less.

Then refill by mass with r-12.

marco5 · #4 07-22-2013, 10:07 PM

I'm doing the following tomorrow.

Fully flushing the system, evap, consendor, lines,
Replacing all orings
Replacing hvac lines with new
Replacing compressor
Replacing expansion valve
Replacing recever/dryer

I'll take some pics, my only question now, what is the best way to put the recever dryer on? As soon as I open the new one I'm exposing it to moisture. Should I vacuum the system fully with the old dryer, open new one and put it on right away (within 5-10 min) and vacuum again? Sorry I don't know alot about A/C systems. Thank you all for the help with this.

Phillytwotank · #5 07-22-2013, 10:17 PM

You just get it in place with the caps on then attach the hose quickly as posible then vacuum immediately then charge.

Phillytwotank · #6 07-22-2013, 10:18 PM

What compressor do you have? Will determine the quantity of oil you'll use.

marco5 · #7 07-22-2013, 10:49 PM

I believe it is the old delco type, it just came in yesterday from the company 4 seasons.

JHZR2 · #8 07-23-2013, 09:58 AM

Yeah minimize time that the R/D is exposed.

Correct job in my book would be to add oil to the R/D, then immediately plumb. Have your gauges hooked up so that you can immediately pull vacuum down. Id shoot for 50 micron, but go as low as your pump can, for as long as your time allows.

Then you should fill at least with nitrogen (optimally Nitrogen with some R-134a) to around 250-300psi and snoop and leakcheck. Once you are sure it is all sound, then evacuate and re-vacuum for as long and low as possible. Then refill with R-12.