What was found
GEG - AT 23,000 RECEIVED A CABIN DUCT HOT CAUTION LIGHT THEN SHORTLY THEREAFTER RECEIVED A FLT COMPT PACK HOT CAUTION LIGHT. COMPLETED THE CHECKLIST AND CAUTION LIGHT REMAINED ILLUMINATED PRESSURIZATION WAS GRADUALLY LOST AND A DESCENT WAS EXECUTED INTO GEG FOR A UNSCHEDULED LANDING. LANDING UNEVENTFUL. PERFORMED CABIN DUCT HOT IAW FIM TASK 21-60-00-810-804 AND FLT COMPT PACK HOT FIM TASK 21-60-00-810-802 CAUTION LIGHTS CLEARED, PERFORMED OPERATIONAL TEST OF THE ENVIRONMENTAL CONTROL SYSTEM IAW AMM 21-61-00-710-803, OPS CHECKS GOOD AND FAULTS DID NOT REOCCUR FAULT CODE 3301. RETURNED TO SERVICE. NO PARTS REPLACED.