I have a 1997 Suburban K1500 5.7 w/rear a/c . 130k . Problam is rear a/c and heat work great . Front heat works . a/c will not cool down below 68 70 . Rear will cool to 55 at top vent and back vent . Front bi leval works fine with heater , but no cold a/c . Just warm air. I can freeze the people in the rear , and get hot in the front . System has charge , any help ? Thanks

The vent door inside of the dash may be broken, which is why it won't switch over to cool air.