My 2000 Tahoe A/C unit is starting to blow less cold than before so I assume either some freon has escaped or maybe it just dimishes its cooling potential over time? I have checked around and most places want to charge around $100 to test for leaks and recharge. My question is, can I do this myself from store bought stuff, or should I just take the plunge and have a professional do it? Seeking advice from anyone who knows the hard core facts! Thanks!!