AC Recharge???

[ebod]

I had an AC shop convert my '89 325i to r-134a about four years ago. My AC now blows cool, but not cold. I'm debating whether to have my mechanic do a proper recharge (e.g., sucking out the old stuff, dye to find leaks, etc.) at $180 vs. buying a can of refrigerant at an auto parts store and doing it myself at $30. How much better is the result if a mechanic does the re-charge?

If I do it myself, what is the best brand/product to use? I'm not sure I want anything that "fixes" leaks because that seems like it could muck up the system (ala tire sealant). I think, however, I'd be OK with something that contained dye so I can find leaks in the future? Do any of these products have dye? Is there any "feature" to avoid?

Thanks in advance for thoughts suggestions.

[superj]

you can add more straight Freon. 4 years and its now just cool is pretty dang good

[aaverhulst]

I agree with superj, buy a can of R134a. Get one with the gauge on it so you tell what the charge on the low side is. If you stay within the green area you should be OK. As it takes 4 years to leak down, I wouldn't worry about it - just add another can or two as needed. Take your time adding as it takes awhile for the system to equalize.

[Jeffnhiscars]

Make sure you purge the air from the hose before you open your LP valve and I buy 12 12oz cans of 134 for $60 get a piercing valve for under $10 and a charge hose. Beats what they charge for those cans at parts stores.