R12 air conditioning compressor oil (Page 1/1)
David Riedle JUL 12, 07:30 PM
Hey everybody!

The air-conditioning did not work on my 13,000 mile Indy when I finally awakened her from her long winter nap a few weeks ago.

I could not find any deterioration visible in any of the hoses, and there was still pressure in the lines. I suspect that the freon is low, since it has never been serviced. On a whim, I found enough genuine R12, and there is a certified shop around here that will vacuum the system and dispose of the old freon following EPA rules, check to see that it is holding vacuum, and put the NOS freon in the system. I purchased new mineral oil from NAPA specifically for R12 to be injected in the system before the R12 is added, so we should be good.

I can not seem to find out exactly how much oil should be added to the R12 system. I can't seem to find it in my shop manual, but I may be looking in the wrong place.

Do any of the Fiero masters know how much new oil should be added to the system when the old oil is removed?

Many thanks!


David Riedle
fierofool JUL 12, 08:07 PM
The total oil for a completely flushed system is 8 oz. 4 in the compressor and 4 in the receiver dryer. If you are simply evacuating the old refrigerant and adding new, I don't believe there's need to replace/add oil. Your certified AC technician should know. If you are replacing the receiver dryer and orifice tube, add 4 oz to the receiver dryer. I would recommend you replace them. Cheap insurance for your compressor. Look at the old orifice tube for heavy contamination in the screen. It may be an indication of the health of your compressor.

Total refrigerant capacity for R12 is 40 oz. for all Fieros.
theogre JUL 12, 08:57 PM
refer oil gets thru the whole system but most is in the compressor sump and acc/drier "can."

Oil capacity is generally X oz w/ ~ ½ to the compressor and other ½ to acc/drier when installed.

Adding oil w/o taking the system apart then oil capacity won't help you.
That's Why most canned Oil Loads from any store have ~ 2oz and often that is too much or too little depending how bad the system is.

I don't know or care what shop is trying to "help" you w/o fixing/replacing old rubber hose and other parts but likely Illegal to recharge w/o doing that.
R12 isn't as bad as R134 but still leak some right thru old rubber hose walls.
If parked for months to years, the compressor likely have or soon will have bad shaft seal and other leaks.
Hoses in the Engine bay gets cooked by the exhaust and often leak at joints to metal. May only leak w/ compressor running, when hot or both.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

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