What was found
PIT - FLT 1140 - EN ROUTE FROM LGA-PIT, FLIGHT LOST PRESSURIZATION AT FL220. DESCENDED TO FL090 AND SET PRESSURIZATION SYSTEM MANUAL. OXYGEN MASKS DEPLOYED NORMALLY. FLIGHT LANDED WITHOUT FURTHER INCIDENT AT PIT. MAINTENANCE FOUND A DAMAGED COMPRESSOR DISCHARGE OVERHEAT SWITCH ON THE RIGHT ACM DAMAGED. REMOVED AND REPLACED COMPRESSOR DISCHARGE OVERHEAT SWITCH. PRESSURIZED AIRCRAFT TO 5 PSI. OPERATIONAL CHECK AND LEAK CHECK GOOD. (M)