a/c oil amount

can anyone tell me how many ounces of oil to put into the a/c compressor on a 1990 cherokee?
many thanks sb

I'm far from an automotive A/C expert, but am a refrigeration tech. First thing to do is figure out which compressor you have. Should be a sticker or shield on there someplace.

The oil in the system migrates, most times the oil is checked after the system has been running for awhile (10 minutes or so) and checked at the compressor with a dipstick. After closing the valves and isolating the compressor. They are three position valves, all the way open for normal running, slightly closed to open the access port and all the way closed to isolate the compressor. Hard to tell how much oil you are going to need as nobody knows how much oil is left in the system?

You can close the in (low pressure valve) and pump down the compressor to avoid loosing freon, you want near zero and not vacuum. Not the type of thing a novice is usually successful with. The sequence is not easy to explain and even harder to do successfully the first time.

Oil level isn't critical, most times it is within an ounce, half an ounce plus or minus. What you don't want to do is overfill, compressors (or piping) can explode trying to pump a liquid.

thanks. the label is gone and i cant find anything on the net. i guess i didnt word my question properly.
does the label on the compressor have the amount of oil that should be in the system? and if so, could some one let me know?
thanks again!

I am also not an automotive AC expert...
It seems right to point out that the RENIX era XJs all came with Frigidaire (GM) compressors. My 1987 XJ was converted to R134a before I bought it. However, I will need to charge it soon and am really interested in the operation of these valves on the compressor. Can somebody (8Mud possibly) please explain in detail the operation of these valves, including direction of turn (CW or CCW)? Sorry for the hijack, I hope I added some value.

MoFo said:

It seems right to point out that the RENIX era XJs all came with Frigidaire (GM) compressors.

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to the best of my knowledge, Renix era XJ's came with the Sanden compressor-- can't speak for the pre-Renix 2.8's, but it's definitely not the old A6 or R4 GM compressor of the 70's and 80's during the Renix years.

MoFo said:

I am also not an automotive AC expert...
It seems right to point out that the RENIX era XJs all came with Frigidaire (GM) compressors. My 1987 XJ was converted to R134a before I bought it. However, I will need to charge it soon and am really interested in the operation of these valves on the compressor. Can somebody (8Mud possibly) please explain in detail the operation of these valves, including direction of turn (CW or CCW)? Sorry for the hijack, I hope I added some value.

Click to expand...

Many, most, all, of the isolation valves are reverse thread. But as soon as you try to form a rule you find the exception lol.

If the stem goes in you are opening the valve for the access port. If it goes all the way in to the seat, you are closing off the compressor. Three position dual function valve for most R 12 systems.

Generally speaking if you can't figure out the hookups, you have no business messing with the system. Sounds harsh but realistic.

I have no idea how much compressor oil SweatyBetty has in the system, so I have no idea how much oil to add. Kind of like draining five and a half quarts out of your 4.0 motor (with the filter) and then asking what the capacity is and finding out it is 6 quarts and then putting 6 quarts in (with a new filter) and being a half quart over full.

MoFo said:

I am also not an automotive AC expert...
It seems right to point out that the RENIX era XJs all came with Frigidaire (GM) compressors. My 1987 XJ was converted to R134a before I bought it. However, I will need to charge it soon and am really interested in the operation of these valves on the compressor. Can somebody (8Mud possibly) please explain in detail the operation of these valves, including direction of turn (CW or CCW)? Sorry for the hijack, I hope I added some value.

Click to expand...

Some of the systems I used to work on had compressors the size of a 4.0 engine. The specifics are different the the theory is the same. I have manged to keep my 87 and 88 A/C going all these years. I'm still using R 12 .