philipswanson wrote:What about the expansion valve? Doesn't that need to be changed to run R12? Some valves specify R134.

R12 and R134 are so close I would not change it

I should have some of the older o ring fittings as long as Tim does not have them.

you can place your R134a cans in hot water to get it into the system. You need to get a full corret charge into it before you can evaluate its performance.

Are you sure that is a resistor in the circuit of the compressor and not a diode?

yes they used expansion valves with internal equalization.

Last I heard, ARA is out of business.

Years ago no one evacuated HVAC systems. They blew R22 thru them and called it good to go.

If the low side is heavily sweating I do not think you're overcharged.

You're close to 30 years on this guy. Spend it.

I think there was an upgrade kit for this using a scroll compressor. My memory is fading and I can not remember. Try Goggle search. I am thinking your older compressors were vane types but can not remember. It is tough getting old.