What was found
(CAN) AIRCRAFT IS IN CRUISE FLIGHT WHEN PILOT SELECTED NR 1 AND NR 2 ANTI-ICE (ON) DUE TO THE OAT AND VISIBLE MOISTURE. ON SHORT FINAL TO THE BASE THE PILOT SELECTED BOTH ANTI-ICE SWITCHES TO THE (OFF) POSITION. IMMEDIATELY UPON ACTIVATING NR 1 SWITCH TO (OFF) THE PILOT HEARD AN AUDIBLE (CLICK). LOOKING DOWN HE NOTICED THAT THE NR1 ANTI-ICE 3AMP BREAKER HAD POPPED. ONE UNSUCCESSFUL ATTEMPT WAS MADE TO RESET THE BREAKER. AFTER THE AIRCRAFT HAD SHUTDOWN THE MAINTENANCE STAFF TROUBLESHOT THE SYSTEM AND FOUND THAT THERE WAS A (DEAD SHORT) IN THE ANTI ICE SWITCH P/N 2840A. THE SWITCH WAS REPLACED AND AIRCRAFT WAS RETURNED TO SERVICE. (TC NR 20070119005)