My '85 MGM, "Maisa"

[friskyfrankie]

86 - 85 All Eng. - 10.00 Oz. Mineral Oil; 52.00 Oz. R-12 (According to Four Seasons Site). They will use PAG with a R-134a conversion. The refrigerant capacity will be different but not certain on the oil. Probably be the same but they may play with the combinations.

[Arquemann]

86 - 85 All Eng. - 10.00 Oz. Mineral Oil; 52.00 Oz. R-12 (According to Four Seasons Site). They will use PAG with a R-134a conversion. The refrigerant capacity will be different but not certain on the oil. Probably be the same but they may play with the combinations.

Thanks, I'll have to verify with the shop anyways. Compressor is prefilled with PAG 46.
The sticker in my car says 1,6kg of R12, which would be 56 Oz.

As long as there's enough oil in it, it'll be fine to fiddle with. Obviously we can now see what happens with not enough oil

[friskyfrankie]

Assuming you are converting to R134a, here is a decent primer of information:

https://griffiths.com/ac-system-help.../r134a-vs-r12/

[sly]

Assuming you are converting to R134a, here is a decent primer of information:

https://griffiths.com/ac-system-help.../r134a-vs-r12/

Quote from the notes at the bottom of the linked article.

We mention using “ester” type refrigerant oil. Some compressor manufacturer’s or OEM’s suggest PAG type oil for R134a. But some types of PAG do not mix well with the old residual R12 mineral oil left in the system components whereas “ester” does mix very well.

This. If you don't clean out the system during a conversion, you can create acids that will eat up various things if the PAG oil and residues in the system get angry with each other.

[friskyfrankie]

ALL VERY true! This is why where the car is taken to is so important.

[gadget73]

If the compressor and drier are new, and the system is getting flushed there won't be any old oil to deal with. PAG should be just fine on a clean system.

[Mainemantom]

The new compressor says it's prefilled with 3oz of pag oil. Is that the full capacity for the whole system?

Don't believe the manufacturer that the proper amount of oil was added. I would drain as much as possible then refill.

[friskyfrankie]

If the compressor and drier are new, and the system is getting flushed there won't be any old oil to deal with. PAG should be just fine on a clean system.

Agreed. As long as the system is completely flushed. Some techs have a problem doing just that.

[sly]

Another thing to do is rotate the compressor by hand a dozen times after being installed before cranking up and engaging the clutch. This can help prevent shipping oil that's stuck in the pistons from blowing out seals. I started doing that after the 3rd replacement and saw that on a power steering pump install sheet (though that's to get lubrication into the pump in that case... instead of getting excess lubrication out of it). Haven't had any die within 6 months so far. Still had the odd one die after 2 years though.

[gadget73]

the NOS one I just put on tonight was damn near stuck initially. Had been parked since late 1983 with oil in it, and it needed some oomph to get moving again. Freed up fine, and I dumped all the old oil out. Mineral oil, and it was so old it looked more like motor oil than the clear-amber color fresh refrigeration oil is. Not using R12 on that one, so the mineral oil is not helpful. I got as much out as possible and put ester in.

[Arquemann]

Parts came today, 48 hours from Arizona to finnish customs, another 48 hours from the customs to me. The customs warehouse is under 45 minutes from me
Gotta mock up the compressor, clutch connector might also be different.

The RA listing said the compressor was prefilled with 3oz, now the compressor box says prefilled with 5.4oz which is supposedly total capacity, 4seasons says total capacity is 10oz.
And the compressor box also says to empty it out and measure anyways

I'll discuss with the shop guys either way.

[friskyfrankie]

Yeah they probably would want to empty the oil so they are starting from scratch. Makes the measuring a little easier or they could empty it and measure but either way a full empty is required.

[gadget73]

The 1984 shop manual says new Motorshaft compressors ship with 10 ounces, which is total system capacity. they say when using it as a replacement compressor, dump 4 ounces of oil out. I have enough fingers to say that ought to leave 6 ounces, so the 5.4 ounces in a replacement compressor is probably a valid number for just a replacement compressor. Its not total system capacity. If you're flushing it all out, it needs another 4.6 ounces dumped in to get it up to full charge.

[Arquemann]

Took the car to the shop friday evening, they called on monday before closing time that it'll probably be done tuesday afternoon, today they called and said it'll be done tomorrow.
They said that the condenser was quite clean, but the evaporator was almost clogged from the glitter and crap... A handful of metal grit and chunks. They've flushed and soaked the evaporator for two days, now it's supposedly totally clean, and they'll get to assembling, filling and testing the system tomorrow.
Guy on the phone mentioned that on initial inspection they'd have recommended to get a new evaporator core, but they were unsure on availability and if any of their guys would want to go pull everything apart for replacement, (on my approval of course) unless absolutely necessary.

Well, this whole thing will end up being a "bit" more expensive than initially though, but I guess it'll be done properly atleast.
Atleast I'll have cold AC when the ol' 302 kicks the bucket sooner or later.

[DerekTheGreat]

No swamp ass is a good thing and worth it. I find myself running the A/C even just to get rid of the humidity.