Additionally, when taking vehicle to a professional a/c service, fist thing they do is evacuate the a/c sytem, pull down to hard vacum & do a drop test. This accomplishes two things: checks the system integrity and removes non condensible gases. Once this is accomplished, they re-fill systen with a known amount (by weight) of hfc134A refrigerant & pag oil. Pressures alone don't tell the complete story about the condition of automotive a/c.

Good info Mark.. I agree pressure doesn't always tell the whole story. However..I've found through manual reading that our cars don't seem to fall into the "normal" pressure ranges.

Thanks for all the info folks. I finally got a little time on my hands so I can go out and mess with it again. I hope I just need to fill it up some more.