need a lesson in A/C

Rustedwrench said
I will tell you what I know about mobile a/c. Most people that work on cars do not understand how it works. If the system was made for R12 it will work much better with R12 in it, assuming it can be made to work. R12 is still available. Those old reciprocating compressors do not like R134a. Old hoses do not like R134a and they can leak badly. Condensers made for R12 do not generally remove enough heat when using R134a. Those cans or a/c fix you buy at the parts store do not contain R134a in general, since that requires a MACS license to purchase. Most parts store a/c fixit cans have a hydrocarbon compound in them, similar to propane. If you to have a shop to work on the a/c system, ask them if they have a micron gauge to use when evacuating the system. If they do, they probably know what they are doing.

I would consider this a all or nothing proposition. If anything needs to be replaced other than a drier, I would junk it all and convert the system to a full system with a Sanden compressor and R134a. Before doing anything I would fill the system with dry nitrogen to check for any gross leaks. If it passes, then vacuum the system, preferably under 50 microns but at least under 500 microns, and if it holds that for an hour it will hold refrigerant.

That's it. That's all I got. I might know more but I can't remember most of what I know, and half of what I can remember is wrong. #-o

You need a 609 certification to buy R12 but can buy R-134A over the counter without certification. You can get a 609 certificate relatively easy and then legally buy R-12.

The "fix-it" kits widely available are known as " death Kits", they contain sealers that in some cases will totally wreck a system. There are two types of sealers used in these kits one is a relatively harmless O ring swelling compound. The second is a silicate formula the turns hard as a rock when exposed to air. This type can totally plug up your A/C system if things go wrong. These kits contain R-134A, not HC refrigerants. Cheap R-12 to R-134A conversion kits are also known as "death kits" because they generally dump in more oil to mix in with the old R-12 mineral oil. R-134A usually turns the old oil into some kind of sludge and the thinking is the new oil will then lubricate the compressor. Good A/C work requires the tools and knowledge of how these systems work. Cheap short cuts and " magic in the can" fixes usually don't end well.

As far as I'm concerned there are only three things you should put in an A/C system- pure R-12 or R-134a, the proper oil and a UV dye to help find leaks. I would never use a sealer of any type, fix the leak.