W123 300d r134a conversion oil capacity - PeachParts Mercedes-Benz Forum

Demothen · #1 07-01-2016, 06:10 PM

Unfortunately my attempts at making sense of the FSM's pages on oil capacity has not gone so well. I am in the process of rebuilding my AC system. I have a new r4 compressor, receiver drier, pressure switch and txv. I have dismantled and flushed the system with liquid flush (4 cans of flush and a ton of compressed air). I am pretty confident that both the condensor and evaporator are clean. Now I am getting ready to reassemble the system and fill it with oil (supercool pag150 per a shop suggested by leathermang). Can anyone explain where and how much oil I should add? I believe I am supposed to drain the new compressor and add oil to it, plus at a few other places in the system.

Again, I have read the FSM for replacing the compressor and checking oil level in the compressor, but I am struggling since I didn't do a flush with a flushing machine.

Thank you.

leathermang · #2 07-01-2016, 06:31 PM

Good , for the record my long time recommended ' guru' is Carlisle Auto Air in San Antonio for the latest industry recommendations..

So, how much oil does your car list on any plates or stickers attached ?

The FSM is not easy to read on oil capacity ... that is for sure..

Ok.. to be clear... you have liquid flushed the condensor and the evaporator and all the lines involved .. and have removed the receiver dryer... and your new one is capped and ready to install ?

Demothen · #3 07-01-2016, 06:41 PM

The only sticker on my car AC related is the one that lists the r12 capacity.
Correct.
I still have the lines all disconnected so that I can easily add oil if needed. Compressor, receiver drier are brand new and sealed.

leathermang · #4 07-01-2016, 07:10 PM

Ok.. to be clear...you liquid flushed the condensor and the evaporator ?

Demothen · #5 07-01-2016, 07:11 PM

Correct

leathermang · #6 07-01-2016, 07:16 PM

Did you make a connection out of the old TX valve ?
What flush brand did you use ?
How much was required to clean the evaporator ?

leathermang · #7 07-01-2016, 07:30 PM

Oil filling capacity of new Delco compressor is 170 cc .
From 83.6-520/3 F4 MB heating cooling FSM Model 123

Accepted R134a substitute amount for R12 is 80 %.

Recommended practice in the FSM is to charge the system with refrigerant then add the oil with an ' oil pump ' which puts oil into the system via the service valve.
If a ' certain ' part of the system is replaced then ' fill a certain amount of oil ' into that one replacement part.

Demothen · #8 07-01-2016, 07:42 PM

I dont recall the brand of flush I used, but it was 4x17 oz aerosol can which came with clear tubing and a rubber fitting on the end. I did not make the old txv into a connector, never heard of that. I dismantled the entire system and flushed each component individually.
I probably used at least a can and a half on the evaporator and another can and a half on the condenser, until I finally got clean fluid out. I flushed each component both directions and blew them out with a lot of compressed air.

leathermang · #9 07-01-2016, 07:49 PM

Ok... that sounds like you can assume no oil left in the system.

Is your compressor on the car or ' in your hand ' ?

Demothen · #10 07-01-2016, 07:55 PM

Compressor is 'in my hand' or more accurately on my workbench, still with the ports capped

leathermang · #11 07-01-2016, 08:12 PM

Good...
Sorta...
the directions in the FSM show putting the compressor into a vise held with a fixture..
with the clutch side down..to remove the ' pipeline'

then turning it over and mounting it with that open pipe hole facing down.

at which time you catch the oil which drains out.... at least ten minutes...

and rotating the clutch shaft several times during that time...

' determine the quantity of oil flown ( not a typo ) out of the original refrigerant compressor and pipeline.

add the same quantity of fresh oil into the new refrigerant compressor through the suction port if a drained oil quantity of more than 40 cc has run out of the removed refrigerant compressor and the system has not been flushed with R11.
If the drained quantity of oil is less than 40cc , add 90 cc into the new refrigerant compressor.

If the refrigerant compressor is reconditioned let the cold-flowing oil run out of the refrigerant compressor as described under item 3. If the drained quantity of oil is more than 40cc , add the drained quantity AND an additional 30cc of oil into refrigerant compressor .
if the drained quantity of oil is less than 40cc , add 90 cc of cold - flowing oil into refrigerant compressor.

Screw on the pipeline while checking the oring for correct seat ...and provide with cold flowing oil ...

Install refrigerant compressor together with the pipeline.

83.6-520/6 F4 MB AC FSM

Individual parts oil when replaced..
condensor 50cc
evaporator 70cc
renew receiver dryer 40cc

30cc equals one oz ...

Demothen · #12 07-01-2016, 08:26 PM

As much as my system was messed up (two clogs, dissimilar oils in the old compressor), I don't think measuring the old compressor's oil is meaningful. If the new capacity is 170cc, I think it makes sense to drain the new one, then add 170cc back to it, and add the specified amounts to the drier, condensor and evaporator. Right?

I think the line "if the system has not been flushed with r11" is the key thing in the FSM. My system should have zero oil in it after all the flushing.

Man, the FSM is confusing sometimes

leathermang · #13 07-01-2016, 08:35 PM

I was just typing up the instructions in the FSM...
the FSM is really confusing...and not just in the AC FSM..

yes.. I think what you said seem reasonable..

Demothen · #14 07-01-2016, 08:40 PM

Thanks for your help! (Yet again)

jack.stew48 · #15 07-01-2016, 10:36 PM

i cant speak to how it goes in a 300d but any ac system i have worked on at the shop we have just added about an oz. at the end. for example, in a Chevy silverado, i replaced the compressor and receiver drier, then once everything was back together, evacuated the air and charged the system. once the system was charged i fired up the car and using an oil pump which injected oil via the low side service valve. i injected about 1 oz. of oil, and the duct temps immediately dropped. i would recommend also adding a bottle of "ice 32" which is a lubrication enhancer. ive seen with my own eyes the 10 degree difference it makes at the vent. it works by lubricating the compressor and condenser, aiding in heat transfer and in the end dropping vent temperatures significantly.

i dont claim to be an expert, just sharing my experience.

best of luck, Jack

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