As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE AIRCRAFT CAME INTO MAINTENANCE WITH THE CABIN HEATER INOPERATIVE. DURING TROUBLESHOOTING, THE IRIS VALVE WAS FOUND TO OPERATE SLOWLY AFTER APPLYING LIGHT PRESSURE TO THE ARM. THE ARM IS CONNECTED TO A CABLE THAT IS ROUTED TO THE FRESH AIR VALVE ACTUATOR BEHIND THE CIRCUIT BREAKER PANEL. THE FRESH AIR VALVE ACTUATOR WAS REPLACED AND THE HEATED OPERATED NORMALLY.