What was found
CRUISING AT 24,000 FEET WITH WING AND ENGINE ANTI-ICE ON, THE CABIN BEGAN CLIMBING UNCONTROLLABLY. CREW FOLLOWED COM PROCEDURES AND PERFORMED AN EMERGENCY DESCENT. FLIGHT ATTENDANT REPORTED A LOUD SQUEAL IN THE AFT SECTION OF THE CABIN. FLIGHT CONTINUED TO DFW AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND A SEAL FROM THE VACUUM RELIEF DOOR ON THE AFT PRESSURE BULKHEAD MISSING AND REPLACED IT. PRESSURE TESTS OF THE AIRCRAFT CHECKED GOOD ON GROUND. AIRCRAFT RETURNED TO SERVICE.