I took my 2006 X3 (approx. 63,000 miles) in to the dealership in July/August 2009 as my a/c was not working properly. Only one vent was blowing sort of cold air, the other 3 blowing hot air. My car was still under warranty at the time. Diagnostics test were performed or so i was told (dye test), no leak found, cause was cited as needing freon and freon was added. Temporarily fixed the problem. This summer 2010, a/c gradually stopped working and has been blowing hot air for about 1 1/2 months. Took car in again, diagnostics test performed (some sort of dye test again) this time told evaporator core is the problem. Quoted $3000.00 all in. My question is, is there a way i can determine if this problem existed back in 2009 when first brought car in for diagnosis. My thoughts are that it did exist back when i was under warranty and diagnosis was incorrect or done improperly. Any suggestions would be appreciated.