Regarding oil just measure the amount you get after draining the old accumulator. Old condenser typically stores about 30ml of oil. So the math would be 30ml + old accumulator oil. Pour fresh oil into the new accumulator's inlet port - one that's connected to the low-side port. Instant compressor damage might happen if you add oil into the accumulator's port that connects back to compressor. Total system oil for 940 is about 200ml. If you're sure the system has never been serviced before only add PAG oil because Volvo originally used that. If you're unsure only then you use Ester oil because it could comfortably mix with PAG.

Regarding oil viscosities use PAG46 only for new compressors, PAG100 for still working old compressors. For ester use POE100 (same viscosity as PAG100). Choose your oil wisely. Much like choosing engine oils. One way is to go for OE oils which there're lots of choice - only pick the one with right viscosity. Notable aftermarket brands are Emkarate (industrial grade) and Supercool. Most easily available at ebay. Other brands are still in grey area.

Amarin.

hi randy,
1. mike is correct, do not open (unscrew the caps of) the accumulator (receiver/dryer) until you're ready to install.

2. oil: goes in to the accumulator, just pour in. i'll check the amount, but the car should have that information located in the engine bay, somewhere.

an observation on the amount. your system will have oil all along inside the components, evaporator, compressor, etc. but most of the oil is in the accumulator. so, the amount should be somewhere less than changing everything, obviously. but you are removing 2 major components.

3. type of oil: use ester. do not use pag oil; that is for compressors designated for pag oil. changing from ester-based systems to pag requires flushing of parts. not needed here.

4. orifice tube: doesn't matter, i choose rein or something like that, but i just get the regular one, not the variable orifice tube.

be sure to note and put it in the correct way--goes in one way only. i presume the tube has never been replaced and it may get stuck. there is a tool that can pull orifice tubes, may be worth to check out.

i run into stuck orifice tubes all the time, part of it breaks off, and part of it is stuck in deep. if it breaks, i remove that section of the ac pipe completely out of the car where it is isolated, get a long screw driver and break it up into pieces. then, thoroughly clean, flush out any residue/broken pieces.

if you cannot get the ac pipe off to isolate the broken orifice tube, then break the orifice tube up and backflush with compressed air to blow out of the ac pipe. cover all open and exposed ac pipes to prevent tube pieces being blown where you don't want them to be.

5. o-rings: be sure to get the o-rings for each connection you're disassembling and have a spare for each connection, just in case one gets cut or anything else. you don't want to wait another week for a spare one. i go for rein at fcp euro (groton).

when installing, just like seals, add a coat of oil on each o-ring when installing.

6. evacuating the system: most people don't have this setup--no small investment, >$500, but by evacuating the system, you save on costs of replacement, but one always lose a little refrigerant even when doing this procedure.

i buy 30lb tanks at a time (6 cars in the driveway).

can't think of anything else at the moment, but hopefully this will help you with some direction.

if you need some help with part numbers for the o-rings, let me know, i'll check.

i know your setup, got a 94 940. great to know you have really low miles. great cars.

regards,
byron golden
86 245
92 245
94 940

Don't remove the caps on the new filter/drier until everything else is in place and you're ready to pull the vacuum. Minimize the time that the drier is exposed to atmosphere to preserve the desiccant inside. If you're using a scale to measure refrigerant that goes in, be sure to account for the bit of 134 you use to purge the gauge/manifold hoses.
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82 242-6.2L; '17 Mazda3; '16 Crosstrek