1990CONV

I am going to replace my compressor on my 1990. About 15 years ago I replaced the condenser. When I recharged the system I never added any additional oil to make up for what oil may have been trapped in the old condenser. I have no clue if I lost any oil. The compressor is starting to leak around the clutch so I purchased an almost new one off a Corvette Forum member. The dry system takes 8 oz of mineral oil. I have plenty of r12 and will continue to use it. My question is has anyone removed their compressor from a similar setup and measured actually how much oil is resident in the compressor? It needs to be a r12 system between years 89 and 91. A newer system with 134A is very different. The missability of the oil in 134a behaves very different then mineral oil in r12. Any info would be appreciated

Kevova

Not 100% sure what you're asking. Since you're replacing compressor you should replace both orfice tube and accumulator. Accumulator catches excessive oil and absorbs any moisture. Many time compressor warranty requires accumulator replacement. Orfice is cheap also indicates if there is debris in system. Seals for hose to compressor maybe different than the originals.
R134a just install retrofit kit. It should come with full charge of PAG oil and 134a along with fittings.
R12 you would drain as much oil as possible from compressor and measure put equal amount in plus 2 for condenser and 2 for accumulator. 6oz would be a guess. R12 requires 525 oil.

1990CONV

Thanks for the reply. I plan to replace the orifice tube but not the dryer. I am going to pull a deep vacuum and hold for quite some time to release if any moisture.

My question as to how much oil is held in the compressor is due to my concern that the system may be a little low on oil. As I noted about ten years ago I replaced the condenser but did not add any oil to make up for what might have been trapped in the coils. The past couple years every spring I have to add about ½ pound of r12 to the system. The car is 28 years old with 30k on it. I am not surprised that a little refrigerant is now weeping out of the compressor by the clutch. I have another compressor to replace it. I can measure what oil is resident in the oil compressor but I am concerned the system may not be at capacity. I am looking for a base line (oil volume) from others who have the similar system that recorded the amount of oil they extracted from their compressors. My gut feel is to measure what I extract and just add another ounce to it. Any input is appreciated.

Kevova

You have the right idea with compressor. There is no set amount in compressor. You let compressor drain out ports into a graduated cup and that should be the amount you add + a little. Accumulator will catch and hold excess oil to a point. Multiple repairs .and adding oil for each; can cause accumulator oil capacity to be exceeded.

Benny42

The beautiful thing about R12 and mineral oil is that 100% miscibility you mentioned in your 1st post. A slight bit of
extra oil will just flow thru the system and not cause any damage. If fill the crankcase, you are good to go as there
is some residual in the rest of the system. I can tell from the question you know not to go too heavy on the oil fill.
I would replace the drier, do you have a micron gauge?

PatternDayTrader

I would say too much oil is way better than not eonguh.

1990CONV

Thanks to all,
I decided to make a change. I purchased a new accumulator. I researched and determined a dry system takes 8 ounces of oil. I will be staring out with a dry compressor, dry accumulator and new orifice tube. The tube has no impact on oil capacity but just wanted to note it will be changed. My original system may be a little on the low side of an oil charge due to a condenser change out about ten years ago. What is the guess as to how much oil to add to account for the new parts. Of course I will be adding the oil manually to them before buttoning the system up and pulling a deep vacuum. Keep in mind I will be using mineral oil and fresh R12.
Thanks

PatternDayTrader

Should work good !

65Z01

My '88 Service Manual states for A/C parts replacement:
- all compressors: if <1oz is drained add 2oz, if >1oz is drained add same amount
- accumulator: add 3.5oz to new accumulator
- evaporator: add 3.5oz
- condenser: add 1oz

1990CONV

Thanks to all