Information Is Power
As I state in my BIO, our purpose here is to arm you with the necessary information to either service your own automotive AC system or procure the services of a *QUALIFIED* ac technician.
First, you must realize that because your mechanic is a brilliant engine or transmission technician does not mean he is qualified or knowledgeable in the repair of an air conditioning system. Human nature being what it is, we like to think we can do it all and while he may sincerely believe he can perform your repair with the excellence he uses on everything else, it behooves you to have at least a rudimentary knowledge of how these repairs need to be done.
AND SO ….
I will bestow on you the magic words that will help insure a good repair.
A high quality repair must always result in A CLEAN, LEAK FREE SYSTEM
No matter what is wrong with your AC system, you must ultimately drive away with one that is both clean and leak free or you will be repeating the repair and possibly paying twice for it.
Moving parts (your compressor) create friction which in turn create wear (read dirt and residue). This is normal. When the dirt becomes excessive it wreaks all sorts of havoc within the system because it acts as an abrasive (creates more dirt) and causes obstructions within the system.
The solution is to chemically flush the system. For a detailed explanation read these two articles:
After reading this you might ask, “So why leak free?”
The answer is refrigerant oil must be “miscible” (a term in chemistry that refers to the property of liquids to mix in all proportions, forming a homogeneous solution) with the freon and travel with it. Ergo, when you lose freon you also lose oil, and we all know what that causes…..More friction and more wear of course. Intuitively you must realize that simply adding freon without oil accelerates the demise of your system and adding oil with the freon over time will lead to a situation where you have no idea how much oil is in the system, which will also cause problems.