What was found
AT APPROXIMATELY 17,000 FEET CLIMBING OUT OF KMEM, CABIN PRESSURE STARTED DECREASING FOLLOWED BY THE CABIN PRESSURE WARNING LIGHT ILLUMINATING. DONNED OXYGEN MASKS AND DESCENDED TO 10,000 FEET. BOTH AIR CONDITIONING PACKS WOULD CYCLE ON AND OFF. COULD NOT GAIN CONTROL OF THEM. REPLACED LEFT AND RIGHT SECOND SEGMENT CLIMB SWITCHES IAW DC9 MM 21-31-09.