Are all the hoses still connected? Any idea why it quite working? Do you know what refrigerant and oil was used the last time it was working?
Most folks convert to R134a and PAG oil, since it’s what all stores carry. However, R12 (Freon) and mineral oil are still available. I have used a vacuum pump and gauges from Harbor Freight and they seem to work fine. However, you can always pay an A/C shop to pull vacuum and add refrigerant once you have checked everything else.
Moisture, dirt and leaks are usually the biggest problems, even if the compressor still works. Hoses are probably older non-barrier hoses, but should work to get by for a while.
- If it’s still sealed you can pull vacuum and get all the moisture out. Then refill with proper oil and refrigerant. Use all new O-rings for hoses and fittings (a full package is cheap).
- To get dirt out you would unscrew all the connections, spray in A/C flush, and dry out with compressed air.
- The orifice is a very cheap part, but may be plugged if there is any debris or dirt. Always replace it. GM white orifice was probably stock, but many use the Ford Blue orifice if it’s been converted to R134a.
- very easy to flush the condenser and the evaporator - similar to cleaning out a radiator. You can drain the old oil from the compressor, but I would not try to flush.