arke

It seems that oils are the main concern. Mineral oil for R-12 and PAG oil for 134a. They just aren't compatible. I am good at mechanics but weak on AC systems. If my system has a leak it is very slow. This car hasn' t been used regularly in over 5 years but still has pressure. The compressor seems to be running fine. I have all the tools IE vacuum etc to do any work but simply asked, would it be most expedient just to vacuum the system to remove all R-12 then install Ester oil instead of PAG, and then 134A or 152a?

Pete_89T2

iTrader: (4)

Vacuuming the system will not get all of the old mineral oil out of an R12 system, so you'll have to do a bit more. I would not recommend an R134A conversion on an FC - you'll probably be disappointed with the cooling performance. The R152A/duster gas will work much better - that's what I converted mine to last year and it gets the car just as cold as R12 did and has been working great so far. Since you say your compressor still works, and because Ester oil is compatible with mineral oil, you can get a 90% + solution by doing the following. To get 100% of the old oil out, you'll need to take the rest of the system apart & flush parts with solvent

1. Pull the compressor off the car and "bench flush" it with new Ester oil. Basically to bench flush, you'll hold the compressor open ports down over a pan & let all the old oil drain out. Then flip it over, add about 30~40 cc's of fresh ester oil into the suction port. Rotate compressor clockwise to circulate oil, then flip it open port side down & drain. Repeat this process several times until nothing comes out but clean Ester oil. If you buy the Ester oil that has the green leak detect dye added, it will be easier to tell when its cleaned of all the old mineral oil. When you're done with this, add your fresh Ester oil to the compressor before reinstalling it on the car with new HBNR (green) O-rings. The amount of Ester oil you'll need to add to the compressor will be the same as mineral oil - look it up in the FSM.

2. Since the system was opened, you should replace the Receiver/Dryer with a new one (they are cheap, typ < $20), and don't forget to use new HBNR O-rings on those fittings as well.

3. Vacuum the system down to 30"Hg, and verify that it holds for at least an hour or more. If it held, there's no leaks, and you can proceed to charge it with R152A per the R152A conversion thread.

Since my compressor crapped out, I had to do the full monty restoration job, which involved a rebuilt compressor (duh!), new receiver/dryer, new expansion valve and flushing every component in system with solvent before putting it all back together with new HBNR O-rings throughout.