Wild Bill

I've got all my A/C components cleaned and back into place. I've added 5oz. of ester oil to the compressor, after draining as much as I could through the inlet and outlet ports. Only got about 2oz. out of fairly clean oil, with only a tiny amount of black particulate.

Most difficult part was the expansion valve R&R, but also had a lot of difficulty getting the 2 bolts that go into the bottom of the condenser put back in. Kind of tricky with the mounting flanges being on a angle... a real pain in the a$$!

Question - How much more oil do I need to add to the system and where do I inject it? Car has only the standard front A/C system and I am recharging with R12. Seems like I've read one place that it requires 7oz. and another that it takes 12oz. Thinking that the 12oz. amount is for rear air equipped. Only got a few dribbles of oil out of the other components and lines.

Thanks,
Bill

fst951

Why are you using Ester oil? Ester works well in 134a, but still isn't quite as good as PAG. Ester is also more sensitive to water than mineral oil. It will work, but it won't be distributed through the system as well. You are probably better off with regular mineral oil. 9-10 ounces is correct. Make sure about 4 ounce of this is in the compressor and 1 ounce in the drier and 1.5 in the condensor and 2.5-3.0 in the evaporator and lines.

Did you evacuate the system yet? You can always ad oil through the guage set prior to the freon.

Good luck

Steve J.

Bill - Here's how I distributed the oil in my '87: Compressor 40% (110cc), Evaporator 35% (100cc), Condenser 15% (40cc), Drier/lines 10% (30cc) for a total of 280cc.

Wild Bill

My mechanic said to go with ester and all that I read on the how-to web pages, said ester... Was that not what was originally installed? Mechanic said PAG 40 was a BAD idea, something about compatability with the compressor and being better suited to rotary-high foam R134a applications.

fst951

Hi Bill,

You are correct about PAG not being used in R-12 systems. It is actually PAG-46 your mechanic probably talked about. Use this only in 134a systems. Ester also is used in 134a systems because it is compatible with 134a refrigerants and slightly tolerable of PAG. R-12 works best with Refrigeration Grade Mineral Oil. Ester will work, but it is not easily absorbed by the refrigerant R-12 like mineral oil is.

Many shops use ester based oils because they only want to carry one oil, not because it is the best! Rule of thumb is mineral oil for R-12 and double end capped PAG for 134a. Can't go wrong as long as the system wasn't contaminated.

Good luck.