I have a 79 F350 with the york compressor. I want to retrofit the AC system . What do I need to buy and what about changing the oil in the York compressor? What type and how much? Anyone have a guide to retrofitting these trucks.
I have access to gages and a vacuum pump and AC equipment.

What is the basic rundown of what is involved.
Thanks

 

The basic rundown is:
-Flush the old oil out of the system. Disassemble and flush piece by piece.
- Drain and flush the compressor (York) with Ester oil.
- Fill the compressor crankcase to the recommended amount with Ester oil. If you look around there is a proceedure for making a dipstick for the York comperssor.
- Replace the Receiver/dryer
- Replace the expansion valve (It's 28 years old and you have to take it out to flush the evaporator).
- Replace the o-rings in all of the connections, including at the compressor. This has nothing to do with compatability, they're 28 years old.
- Ideally you would have the POA or STV recalibrated for R134a. It will work ok without this, but doing so will give the best performance.
- If the fan clutch is more than 8-10 years old, replace it with a new Motorcraft clutch.
- Evacuate the system with a vacuum pump for 40 minutes at 28-29".
- Charge with R134a, start with 80% of the recommended R12 charge.

Keep in mind that the shaft seal on the compressor could be bad. It can be replaced, but special tools are needed. You may be able to find a shop the do the seal for you.