What was found
SEA FLIGHT NR 2322: WHEN SELECTING PROP HEAT ON, ADVISORY LIGHT ILLUMINATES FOR LEFT PROP, THEN APPROX 5 SECONDS LATER, PROP DEICE CAUTION LIGHT ILLUMINATES. RESET ONCE AS PER E/A CHECKLIST AND SAME THING HAPPENS. RIGHT SIDE PROP DEICE OPERATES NORMALLY. MAINTENANCE FOUND 'OPEN HEATER', 'OPEN B' AND 'OPEN C' CDS FAULTS FOR THE NR 1 TMCU. PERFORMED THE ELECTRICAL CONTINUITY CHECK OF THE PROP DEICE IAW AMM 30-61-00, PG 508-511. NO DEFECTS NOTED. CLEANED CONNECTORS AT THE NR 1 TMCU AND NR 1 BRUSH BLOCK. PERFORMED THE PROP DEICE FUNCTIONAL TEST IAW AMM 30-61-00, PG 501-502. OPS CHECK GOOD. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.