What was found
DISCREPANCY: THE PILOT DEPARTED KPHX HEADING TO KOLS. DURING THE CLIMB, THE PILOT REPORTED THAT THE RIGHT WING OVERHEAT ANNUNCIATOR ILLUMINATED. THE PILOT REQUESTED TO ATC TO RETURN TO KPHX. AFTER PERFORMING QRH, APPROXIMATELY TWO MINUTES LATER, THE CABIN STARTED FILLING UP WITH SMOKE. WHILE DECLARING AN EMERGENCY AND TALKING TO ATC, THE SMOKE CLEARED OUT. THE LANDING WAS WITHOUT INCIDENT.
CORRECTIVE ACTION: MAINTENANCE INSPECTED THE AIRCRAFT AND FOUND THE AC CIRCUIT BREAKER POPPED FROM SUSPECTED PROLONGED USE OF THE MANUAL HEAT ON HIGH SETTING. MAINTENANCE PUSHED CIRCUIT BREAKER IN AND PERFORMED ENGINE RUN WITH HEAT ON. NO CABIN SMOKE DETECTED AND RIGHT-WING OVERHEAT ANNUNCIATOR LIGHT DID NOT COME ON. THE OPERATIONAL CHECK WAS NORMAL AND THE AIRCRAFT WAS RETURNED TO SERVICE.