My bride of 34 years was given her parents car. It’s a 1985 xj6 vanden plas. It’s been setting for the better part of 20 Years. Family mechanic fixed fuel system. I replaced the cam covers they were raining oil. The AC is not working, i grew up on a horse ranch in Idaho so.that part to make my brides ride awesome I am clueless. I put gages on the system and there seems to be no charge so I put a vacuum pump on it held solid for two days. I know ester oil but not sure how much or even how to get it feed into the system. I think I can Fix it for her, just unsure, bought a new dryer. Any help would be great, love the car, so many Awesome memories before her dad past.

 

Google Convert from R12 to R134-A refrigerant and you will get a lot of opinions from a lot of experts. Purchase your adapters and note that you need a lesser amount of R134-A versus the older Freon by a 1/2 a pound.
Go for it.

Larry Louton

 

if you don't know what kind of oil is in the compressot, you will need to flush the system with a special machine. Even if there is no refrigerant in the system, there is oil, and R12 and R134a require different oils.

Instead of wasting time with R134a, which does not cool enough, find an alternative compatible refrigerant to R12, unless you know for a fact that the system was converted to R134a already..
R134a requires barrier hoses, other alternative refrigerants don't.

otherwise you run the risk of creating a mess requiring replacement of many system components.

you can always take the car to an a/c shop that has a refrigerant-analizer machine and save a lot of potential headaches.

 

Hi Rob
here's a link to someone who has done the conversion. This is just the final observations but it's quite a good read.
https://www.jaguarforums.com/forum/x...estion-220684/
Con

 

Very hard to get good results with R134 in hot weather but here are some tips that work for me. I have lots of old cars and here is what I know.

You need to use about 75% charge with R134

You need to keep the condenser far cooler with R134 vs R12 and adding a pusher fan in front of the condenser is mandatory to keep the condenser cool so the R134 changes back to a liquid and accumulates before it's sprayed into the evaporator.

Pressures need to be far higher with R134 so if any of your hoses are questionable they will fail or leak quickly becasue R134 molecules are smaller than R12 too.

You can only get marginal performance UNLESS you change or adjust the expansion valve. R134 needs a slightly smaller oraface so it can get to the higher pressures (250+ PSI) needed for proper R134 expansion. Some R12 expansion valves are adjustable.

Ester oil isnt great. It really doesn't mix all they well with R134. This is less of a problem with compressor that sit low but on the XJ6 the compressor sits high and probably wont last all that long if you dont get the the oiling situation right. I'd suggest removing and draining the compressor and flushing it with an aromatic like mineral spirits. The evaporator is far more difficult to remove so a but has no moving parts so a flush can be used. Same for the condenser and lines then use PAG oil.

Just dropping in R134 with ester oil will result in a system that cools fine in cooler weather, on 75 degree days perhaps, but if you get caught in slow traffic on a 80+ degree day you may find your vent temps rising fast and all cooling gone. R134 performance rolls off very abruptly as temps rise.

Avoid using drop in replacements. Most are flammable and dont live up to their hype.