Reply to "R - 134 Conversion"

R-134a will work in your old system if you do this:
1)- change to a rotary AC compressor. Theese have no oil sump, so 'cleaning' the old oil from your system is much simplifed. Ther stock York has a sump, which must be thotroughly cleaned before reinstalling it.
2)- use 'barrier-type AC hoses, with o-ring seral ends. Any shop can make these up to size. R-134a is a physically smaller molecule and leaks more readily than R-12.
3)- change the under-dash expansion valve to one calibrated for R-134a, probably without the filter-screen that was commonly used with R-12.
4)- change the dryer in back to a new one. The old unit is hopelessly contaminated with R-12 oils and uses the wrong dessicant for R-134a anyway.
Your favorite Pantera parts vendor has already made up a 'kit' of these parts that takes care of all this for you, and it may be cheaper than running all over town chasing down the various bits to fabricate such a conversion. Installation of the new hoses running through the center console and connecting them under the dash without damaging the evaporator is not a walk-in-the-park, either.....