What was found
GEG FLIGHT NR 2351: AT CRUISE ALTITUDE (FL240), CABIN PRESS MASTER CAUTION ILLUMINATED. CABIN ALTITUDE GAUGE SHOWED AT 11000', THE CREW DESCENDED TO 14,000 THEN 10,000' MSL, CABIN CONTINUED TO CLIMB. ACCOMPLISHED DEPRESSURIZATION CHECKLIST AT 2-3 MINUTES AFTER CABIN ALTITUDE HAD ILLUMINATED. NR 1 BLEED HOT CAUTION ILLUMINATED. ACCOMPLISHED BLEED HOT CAUTION CHECKLIST. MAINTENANCE REMOVED AND REPLACED THE PACK FLOW CONTROL VALVE IAW Q400 AMM TASK 21-52-01-000-801 AND 21-52-01-400-801. OPS CHECK GOOD. GROUND PRESSURE CHECK GOOD. OCF PERFORMED AND WAS SATISFACTORY. AIRCRAFT RETURNED TO SERVICE.