As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SLOW BUT STEADY LOSS OF CABIN PRESSURIZATION AT FLIGHT LEVEL 350, FOLLOWED BY ODOR OF HEAT FILLING THE COCKPIT. EMERGENCY DECLARED. SELECTED HIGH PRESSURE BLEED OFF. ODOR PERSISTED. BELOW 10,000 FEET, VENTED AIRCRAFT, ODOR GONE. INSPECTED TAIL COMPARTMENT WITH ENGINES AND APU RUNNING. NO LEAKS NOTED. PRESSURIZED AIRCRAFT WITH ENGINE AND APU PNEUMATICS. NO ODOR NOTED. REPLACED THE RIGHT CABIN TEMPERATURE CONTROL VALVE IAW DC-9 MM 21-60-00. OPS CHECKED GOOD.