2000 Z71 A/C Fan Belt Breaks

I have had four A/C fan belts break during the past 6 months or so. There are no noises. Things work fine for a while and then without warning the belt breaks. All pulleys, clutch, etc. appear to be OK. This is the 5.3L V-8 which has a separate belt for the A/C. My mechanic says he heard there is a computer problem causing the belts to break that only the dealer can correct. Naturally the dealer never heard of such a problem. Can anybody help?