My Miata is a 95 and I'm in the process of plumbing the A/C. I'm using a remanufactured Ford compressor that came charged with 3 ounces of PAG of unknown weight. I'm also using a new condenser, dryer and Jason's hose kit. I blew air through the rest of the system when I had it apart. According to the Miata decal on my hood, the system uses 8.75 oz of PAG 100 and 21 oz of R-134. My initial thoughts were to use what's on the decal, but I know nothing about A/C. After doing some research, I think my Ford compressor may have PAG 46 in it. My research has also lead me to believe that the 8.75 ounces is the total amount for a new system and mine may still have some residual oil in it. So for those of you who have already done this or others who have any opinions, I'm all ears. Thanks.

 

I believe the oil is specific to the compressor so use the info for the compressor application (type and how much). Maybe reference a Mustang for the appropriate year if that is what the compressor is for.

However, is the compressor for the later Mustang years designed for 134A? (not R12).

 

I talked to a tech from the remanufacturer (4 Seasons). He said that my compressor is used in an R12 system so it has mineral oil in it. He said to drain it out and use PAG 46 to make it compatible to a 134A system. He also said the amount needed would be specific to the car's system. So I'm going to drain the compressor and use about 8 oz of PAG 46.

 

Good to know as I am going to be running in to this shortly and had similar questions.