Compressor was seized up.

figured if I'm replacing that, might as well convert over to r134a. I DID NOT use a retrofit kit. I used retrofit fittings, and used a measured amount of ester oil, which is compatible with residual r-12. I did not want leak sealers or anything else in there.

Bought a new compressor for $75 on craigslist. Also got a new receiver/drier,new o-rings and belts. Should have replaced the h-valve, but didn't.

Had the old r-12 removed. Then had a holding charge of nitrogen and a trace of 134a put in it around 50psig. Checked everything with a leak detector, picked up some residual around the valves, but no real leakage.

Replaced the compressor, receiver/drier and o-rings Put new Ester in the compressor and drier, and pulled a deep vacuum on it for 2 hours, Let it sit overnight, and it didn't lose any vacuum. Put the vacuum back on it in the morning for 30 minutes anyway, double checked it, then charged her up. Ended up putting in about 28 ounces of refrigerant, which is about 80% of it max capacity of r-12. I will put the gauges back on it as soon as we have a warm day. It was only 60 today.

Ran it for awhile, nice and cold. Let it sit and went over everything with the leak detector again.

So, I went all summer without AC and fixed it just in time for the cold weather. It wasn't my plan, but the clutch hub on the old compressor was almost cashed out, along with the belt.