I need to retro fit my AC system from R12 to R134a. My problem is I need to remove all the old oil from the system but I can't find anything on how to do that. Do I have to take the compressor out and manually remove the oil and then flush the AC system?

 

If the system is empty, open it up, pull the receiver/dryer, (you should really replace that part....) and blow out the system. Probably have to flush the compressor. (good idea in any event.)

 

So this is getting interesting I just looked at the AC system and the R134a adapters are already installed. Could this possible that the previous owner already converted it?? Let me what y'all think. should I go ahead recharge it with R134a ?


high side port

low side port

 

That, or R12A or some other "R12 replacement" refrigerant.

RwP

 

R-12 and R-134 hardware will not connect to each other. My '93 GMC had the R-134 fittings and when I charged it with R-134, it's been working a year with no issues. I'm thinking someone already converted it.

 

Actually RalphP is right it is R12a I just didn't know it even existed! The difference is for R134a has a different fitting for the low side and R12a has the same fitting for both low and high! Thank you guys for the input it helped a great deal!

 

Quick Update on this issue I was able to fix and figure out that the original was R134a all along! I guess they converted it before it left the dealership lot in 93! LOL I am glad I never put different type in after all. I took tons of research and talking to the previous owner ( he was the second owner of this truck.) It works like a champ now AC runs cool.
Thank you to everyone for their help and advice! You guys rock!

 

I bought a '93 Dakota in '93. The salesman told me they were in the process of changing over to R-134 in '94. If I needed warranty work, it would be converted to R-134 as R-12 was getting hard to find.

 

I bought my ‘93 in September. There were only 6 left on his lot and they were trucking in the ‘94s as I was there. Mine is R12. At least that is what all the stickers say.

I have never charged the system and it still blows cold air. This one definitely falls in the category of “if it aint broke, don’t fix it”.

 

R-12 is superior as far as cooling. It was coincidentally banned when the Dupont patent expired. It's less likely to seep through the hoses due to the molecule size. Think wire gauge. The smaller the number, the larger the molecule. There was a push to outlaw R-134 but the newer refrigerant tends to catch fire.