Working on AC Questions...

[JOSEPH TICHY]

Listers: 

All of this talk about AC refrigerant upgrading [and my future summer project of replacing my compressor and upgrading to R134-A] has got me thinking about how one should proceed working on these systems.

Of all of my German cars, I too have never had functioning AC.  I have never even touched these systems internally/externally, save for removing the belt to loosen up some crankshaft drag.  Thus, working on AC systems is the one part of the car I've NEVER touched.    

My question, then, is what is the first step to work on these system?  There are enough WARNINGS and labels on the system to make a tort lawyer's day!  I don't know enough about the "magic" of how AC works, but knowing that there is noxious gas under pressure  in the system (in theory), I assume that I should NOT just crack a bolt and start removing things.  

My symptoms:   blown compressor manifold seal as evidenced by oil all over the compressor and the clutch never engaging.  

I took the car in to get  an R12 recharge about 2 years ago and the wrench informed me that "it didn't hold a vacuum" and said I would need to replace the ENTIRE system.  Of course, the local guys love to jump to "worst case scenario" so I ignored his suggestions and began learning about  the system parts and will try to replace all necessary parts myself.  I need to know what I need to do to first before I begin replacing parts.  

If the system blew a seal, can I assume that all refrigerant and oil is out of the system?

Can I test for pressure with something as simple as a tire gauge?  (This would presuppose a shrader valve is on the AC system).

If there is no pressure (and presumably no freon in the system), is that when it is OK to begin cracking bolts and opening the system?    

Should I take the car in and have the system flushed and cleaned out before beginning to replace parts, just to make sure all freon and crap is out? 

Should I FIRST replace the parts, THEN have the system flushed and filled with the new parts installed?

Do the R134A kits come with an evacuation can for the conversion?

How do you add oil to the AC system?  Is there a fill spot, or do you just pour it into the AC compressor when uninstalled?  

Any guidance on how to begin working on AC for the first time, would be greatly appreciated.  I am not concerned with R&Ring the system once evacuated (I know what parts to replace and how)...I just need to know what I need to do to begin SAFELY removing parts and cracking nuts open. 

Thanks in advance. 

JOBE