so i looked at and old r12 walk in currently on 409. it has no t-stat or pump down solenoid just lp control. so i wanted to add t-stat and solenoid, but with 409 at 600 dollars a jug, cant justify buying it. may be a long long time until it all gets used. RSD suggested replacing condensing unit with a 134a unit, and then just use current txv and evap, add lls and stat. condensing unit and coil are both 10,000 btu, and looking at load calculations i should only need about 8,000 btu.
so- with a good system flush, drier, and new condensing unit, does this sound like a decent plan? other thought was a 404a condensing unit, but unfortunately with the way the evap fits in this cooler i would have to take entire coil down just to replace txv because side access panels are blocked by cooler walls.