A/C Restore

[hatzie]

If you look at the manuals thread in my signature there are several GM service training textbooks on GM A/C systems. The 1973 service manual has some excellent theory of operation info in a shorter format than the service training textbooks but the textbooks are very thorough. The 1984-1991 service manuals will have some specific information on your system. I scanned the 1995 service manuals as well so...

1995 should still have the same barely adequate Harrison R4 pancake compressor that your 1984 started its' life with. If it's on the same side of the engine as the 1984 compressor and clocked the same way you should be able to just use 1984 lines after replacing the flexible sections with R134A barrier hose.
You'll need to replace the accumulator/dryer and orifice valve with fresh units along with swapping all of the o-rings and gaskets in the system with R134A compatible stuff. Obviously you should unseal and install the new dryer dead last... just before you pull a hard vacuum on the system to keep the moisture contamination of the fresh new dessicant to a minimum.
You'll also need to replace or remove any mufflers in the hard lines if you're re-using them... note I'm not entirely sure GM used AC mufflers on the CK trucks in 1984. They did on the A6 on my 1976 so I'm just covering my bases here.
I would recommend emptying the compressor and changing the unknown pedigree compressor oil to Polyol Ester oil with UV leak detection dye. I would also thoroughly flush any hard parts you intend to re-use... hard lines, condenser, and evaporator etc to get rid of all the leftover Mineral oil bugs, dirt, etc that you can possibly flush out.