Problem with A/C on 2000 Suburban

[Lost-Bunch]

Yes, put several new belts on, even one that was a little shorter. What seems weird to me is the fact it works great, put a new tensioner on and it will last about a week or two then over extends and breaks the belt. The compressor makes no funny noise's unless the tensioner is contacting the pulley. The local A/C repair shop said to replace the system around for 1000.00 but they can't tell me whats wrong with mine ? They are the ones who put gauges on it and said it looked fine, but said that the compressor must have something wrong with it and clogged the rear expansion valve.