As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE AND FUMES IN COCKPIT WHEN HEATER TURNED TO FULL INCREASE. HEATER OVERHEAT ANNUNCIATOR DISPLAYED. POSSIBLE CAUSE: DUST OR DIRT IN THE SYSTEM. MECHANIC RESET CIRCUIT BREAKER AND OPERATIONALLY TESTED FOR 30 MINUTES WITH NO DEFECT OR MALFUNCTION.