What was found
AIRCRAFT WAS GROUNDED: FLIGHT AIR RETURNED TO IAH ON ACCOUNT OF PRESSURIZATION ISSUE. EMERGENCY WAS DECLARED. MAINTENANCE ACCOMPLISHED OPERATIONAL TEST AND LEAK TEST OF THE PRESSURIZATION SYSTEM IAW AMM 05-51-91, OPS AND LEAK TEST GOOD. ACCOMPLISHED OPS TEST OF THE CABIN OUTFLOW VALVE IAW AMM 21-31-03, OPS TEST GOOD. ACCOMPLISHED BITE TEST OF CPC IAW AMM 21-31-00, NO FAULTS FOUND. ACCOMPLISHED BITE TEST OF THE PACK/ZONE TEMPERATURE CONTROLLER IAW AMM 21-61-00, AIRCRAFT PTC BITE GOOD. AC RETURNED TO NORMAL CONFIG. AIRCRAFT OK FOR SERVICE. PERFORMED GVI OF CABIN OUTFLOW VALVE, NO DEFECT NOTED.