Correct Refrigerant Oil Quantity Upon Compressor Renewal
 

2016 C300 - 205.048, with 274.9 motor; equipped with R134a.

Have to renew refrigerant compressor on this vehicle due to failure of compressor's integral refrigerant metering valve.

New dealer supplied compressor is labeled 000 830 30 02 80; label states ND-oil 12; 80 cm3.

In preparation for compressor renewal, the system's refrigerant was evacuated; no oil was extracted.

WIS article AR83.30-P-1760LW (Drain, Evacuate and Recharge) details the following lubricant refill quantities specific to this vehicle:

a) Compressor oil extracted during evacuation - 0 cm3 [none was extracted]

b) add new oil to the refrigerant circuit according to the oil filling capacity noted during extraction - 0 cm3 [again, none extracted]

c) additional oil filling quantity after replacement of refrigerant compressor - 20 cm3 (per BF83.55-P-1007-01J)

d) additional oil filling quantity after replacement of desiccant cartridge - 20 cm3 (per BF83.55-P-1009-91J)


As such, according to these quidelines, installation of a new compressor and desiccant bag in a system with no history of refrigerant loss or other faults/component renewals and no evacuation of lubricant during removal of refrigerant from the system should have 40 cm3 of ND-oil 12 added prior to recharging.

The new compressor was bench mounted, inverted, clutch rotated and found to contain less than 5 cm3 of lubricant.

Question is... to what does the 80 cm3 on the new compressor's external label refer? The unit was purchased new from Mercedes, was not pressurized and contained no lubricant volume of consequence on board.

Does 80 cm3 represent the system's total refrigerant oil capacity?

What I typically do under these circumstances is find out total capacity and back out x for condenser, x for dryer and x for evaporator. That calculated amount is what I put in compressor.

Neglected to mention that an attempt to drain oil from the existing old compressor was also met with no oil obtained.

With regards to totaling oil in system components, the following values are listed in the WIS document (AR83.30-p-1760lW; Drain, Evacuate and Recharge Air Conditioning, check for proper operation and check for leaks) for this vehicle:

Condenser - 20 cm3

Evaporator - 40 cm3

Suction line - 20 cm3

Pressure line - 20 cm3

Compressor - 20 cm3

Dessicant bag - 20 cm3

Total of System Components: 140 cm3

Again, the compressor body is labeled 80 cm3... I'm uncertain as to whether that figure represents the system's total oil capacity or something else.

I would not be that concerned about what the compressor says.

Another way to approach it is to disassemble and blow everything out prior to compressor install, replace the dryer then add the total amount the system takes. Put some into the hose ends and the remainder in the compressor.

The reason for this hassle is that WIS fails to list the proper value for this W205 C300 equipped with R134a.

Step 14 of the main document ("Refrigerant compressor, remove/install" (AR83.55-P-5310-LW)), entitled "Correct Oil Level of Refrigerant Compressor" refers to article AR83.55-P-5310-02MNM, "Correct Oil Level of Refrigerant Compressor."

Unfortunately, that article refers only to refrigerant R744 compressors - no mention whatsoever of R134a compressors which this MY 2016 vehicle is equipped with.

By chance, does the 80 cm3 listed on the compressor's label possibly refer to the compressor's displacement and not a PAG oil fill value??

You're making this more complicated than it is. The old compressor is obviously scrap now, so drain out whatever parts you're removing into a container, measure, and then put that same amount back in. If you take out none, but you're concerned, then add 2 or 3 ounces.

A lot of oil will be in the evaporator if the system was running low on refrigerant. So instead of relying on the WIS by MB

Use the old instructions of chrysler etc, they had this in detail. They told you where most the oil would be when a system was used in certain different conditions.

Anyway,

Remove the txv and flush out every part except manifolds. Purge wirh nitrogen and some refrigerant added to lift the last remaining oil and cleaner residue.

Empty the new compressor and refill the correct type oil total capacity at various places of the system.

If your compressor is the variable type, then dont fill the ports, it has a crankcase fill bolt like the harrisson V5 (to be honest the Denso variable swash plate is a rough clone of the old V5)

Pull a solid vacuum and liquid charge the system if you can (large 30lb cylinder)
If you are using cans, then careful measure is required, (every can will lose an ounce for purging the charge hose unless you have a valve on the hose end)