What was found
PBI-FLT 1681 - AFTER TAKEOFF FROM PBI, AIRCRAFT PRESSURIZATION APPEARED TO OPERATE NORMAL UNTIL ABOUT 5,500 FEET. THE AUTO FAIL LIGHT ILLUMINATED AND PRESSURIZATION SWITCHED TO STANDBY. AIRCRAFT DIFFERENTIAL CONTINUED TO CLIMB. SWITCHED OVER TO MANUAL AND HAD NO CONTROL OVER THE OUTFLOW VALVE. OUTFLOW VALVE INDICATED FULL CLOSED. OUTFLOW VALVE HEATER CIRCUIT BREAKER POPPED AND WOULD NOT RESET. FLIGHT RETURNED TO FIELD AT PBI AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE FOUND WIRES DAMAGED AFT OF THE AFT CARGO BULKHEAD. REPAIRED WIRES. ALSO, FOUND WIRES AT THE PRESSURE CONTROL PANEL DAMAGED. REPAIRED WIRES. REMOVED AND REPLACED CABIN PRESSURE CONTROLLER. RESET OUTFLOW