What to do with an inoperative R12 A/C system.

[morcey2]

I've got an 84 K1500, 305, 700R4 that has non-working A/C (R4 rotary compressor). This became very apparent yesterday when it was about 110 in the cab on a 65-degree day. The A/C hasn't been converted to 134A and it doesn't seem to currently have any refrigerant in it. Pushing in the valve on the low side gives a very slight hiss, but not what would be expected from an even semi-charged system.

I want to have a working A/C this summer, but I don't want to spend hundreds on it. (I may have to though.) I used to be EPA certified, but that was many moons ago. Doing a correct R134A retrofit will probably cost several hundred (new hoses, o-rings, accumulator, orifice tube, possibly compressor, and switches since the pressure will be different.

I'm going to get it pumped down and see if it will hold a vacuum. If it does, which I doubt it will, I'll probably just stick w/ R12. If it doesn't hold, that's where the real decision making will have to happen. It's hard to find a leak without some type of pressure in there to move things around. Doing a full R134A conversion before finding the leak could mean replacing the entire system anyway. (A 'Why didn't I notice that bullet hole in the condenser before?' moment.)

Anyone have any leak-finding tricks that might help here? I'm already assuming I'm going to have to drop at least $200 on this, but I don't want to. At least with an empty system, I don't have to pay someone else to recover the old refrigerant.

Matt