Refrigerant / Oil Capacity on W108 with A6

[Bezant]

Hi guys,

I finally have access to the proper AC machine to do an evac and charge when I replace my compressor and drier. Since the old ones have been leaking, I'm not sure about a baseline amount. How much r134 and pag oil should I plan to add?

[BWhitmore]

The compressor should have a label identifying the amount of R134 and the amount of compressor oil required.

[Tomguy]

Unless you plan on flushing or replacing the evaporator and condenser, you won't want to use PAG, it isn't compatible with the OEM R12 oil unless it's already been converted to PAG. Also, the condenser won't work that well with R134a. Is this a system that's been previously converted to R134a?

[Bezant]

Yes, it's converted and worked nicely when it had charge. No info for capacity on the new one, maybe hiding on the old one.

[vandor]

I replaced my compressor 2 weeks ago. Someone on FB posted a pic from the factory repair manual that said that the compressor needed 0.25 liter of oil. I tihnk that is just a bit over 8 oz, but double check. I drained the oil that came with it and added that amount of Ester oil.

[Tomguy]

If the new compressor came with no oil in it, I would suggest 4-6oz. This is if your system has NOT been flushed. There will be oil still in the old condenser and evaporator. You don't want to overfill with oil. You're replacing the dryer so maybe closer to the 6oz. YMMV and I would suggest looking for a specific A6 compressor spec sheet. Here's an R134a system in a car I have with the FSM fill guides.
While this is for a Chrysler LH platform the guide is pretty much universal for R134a systems with a roughly 25oz R134a capacity:

COMPONENT NAME ml. oz.
Total Air Conditioning System 150 ml. 5.00 oz.
Condenser 30 ml. 1.00 oz.
Evaporator 59 ml. 2.00 oz.
Filter/Drier 30 ml. 1.00 oz.
Line Blown 44 ml. 1.50 oz.

VERIFY REFRIGERANT ND8 LUBRICANT LEVEL
(1) Discharge refrigerant system using a recycling/
reclaiming equipment if a charge is present.
(2) Disconnect refrigerant lines from A/C compres-
sor. Cap the open lines to prevent moisture from
entering system.
(3) Remove compressor from vehicle.
(4) From suction and discharge ports on top of
compressor, drain lubricant from compressor.
(5) Add system capacity minus the capacity of
components that have not been replaced. Refer to the
A/C Component Refrigerant Oil Capacities chart
above. Add lubricant through the suction and dis-
charge ports on compressor. This is not to exceed 150
ml. (5.00 oz.) in total.
(6) Install compressor and connect refrigerant
lines. Then evacuate and charge refrigerant system.
(7) Most reclaim/recycling equipment will measure
the lubricant being removed. This amount of lubri-
cant should be added back to the system. If a new
compressor is being installed, drain lubricant from
old compressor, measure the amount drained and dis-
card old lubricant. Drain the lubricant from the new
compressor into a clean container. Return the
amount of lubricant measured from the old compres-
sor, plus the amount reclaimed from the system back
into the new compressor.

[vandor]

This is the manual page I was referring to.