What was found
DURING CRUISE FLIGHT, CREW REPORTED A FWD EQPT OVERHEAT EICAS MESSAGE DISPLAYED. IAW QRH CHECKLIST, SWITCHED TO OVERRIDE POSITION. AFTER 20 MINUTES CABIN ALTITUDE MASTER WARNING DISPLAYED. CONTINUED TO FOLLOW CHECKLIST, COULD NOT CONTROL THE CABIN ALTITUDE. EXECUTED EMERGENCY DESCENT AND DECLARED EMERGENCY. DIVERTED AND LANDED WITH NO INCIDENT. AIRCRAFT GROUNDED. REMOVED AND REPLACED THE LEFT PACK FLOW CONTROL AND SHUTOFF VALVE. REMOVED AND CLEANED EQUIPMENT COOLING AIR CLEANER. OPS CHECKED SATISFACTORY. NO FURTHER DEFECTS NOTED. REMOVED AND REPLACED PRINTED CIRCUIT, COOLING INDICATION CARD AND MANIFOLD INTERCONNECT VALVE. COMPLIED WITH EXCESSIVE CABIN PRESSURE LEAK TEST. NO LEAKS NOTED. OPS CHECKED SATISFACTORY. AIRCRAFT RELEASED FOR SERVICE.