I just did my 79 Impala that had R12 and the large compressor. All I had to do was get the system evacuated, change the evaporator filter, the O rings, add the new compressor oil, and then fill it up with 134. Working great so far. jim
Thanks for your input, Jim. I had removed the large A6 compressor to swap over to the R4 radial compressor. I will be going with a parallel flow condenser which is supposed to work better with the 134A refrigerant. I figured while I was at it, I'd also replace the evaporator, accumulator and orifice tube.
compressors on 83 Malibu are the same regardless of refrigerant, get one from autozone for your car, let them look it up. you HAVE to change the accumulator drier and orifice tube and I HIGHLY recommend a complete flush of entire system, put the right oil in the compressor directly, then after install DO NOT crank, hand turn the compressor several times to push oil into hoses (compressor cant compress oil). then I suggest having a shop pull a vacuum and recharge it for you, but if you do this on a dry day ive had decent results with no vaccum and self charging. learned the hard way on my 83 Malibu and burned up original compressor had to go back and redo everything, on my 99 alero and 98 deville, I changed the compressor, chances are that's why it doesn't work anyways, front seal gone, also change the o rings all out on a car that old (use the ones for 134a) both my sucsefull attempts I changed the above and charged myself, the aleros ac ran longer than the original, the devilles was still working when it blew a head gasket, ****ty northstar motors!
AshTray has a good point. When changing compressors, they now come pre-oiled, but you are required to hand-turn the compressor shaft 15 turns to get the excess oil out of the piston/swash plate area and into the discharge line. Even though you don't have to pull a vacuum to recharge, you have to pull a vacuum to remove air, moisture and help see if there's any leaks before recharging. Pulling vacuum also makes it very simple and fast to get the majority of refrigerant into the system as you charge it and allow you to just turn it on instead of cycling the compressor on-off several times before finishing the charging.
