What was found
WINDOW HEAT POWER, RIGHT FRONT CIRCUIT BREAKER TRIPPED DURING PREFLIGHT INSPECTION. ACFT GROUNDED. ACCOMPLISHED CIRCUIT BREAKER P6-12 C394 INSPECTION, NO DAMAGE NOTED, RESET THE CIRCUIT BREAKER IAW AMM 20-60-06-860-801. WHCU M323 NO EXISTING FAULTS, FAULT HISTORY LOGGED "P5-9 CONTROL POWER". CLEARED FAULT, RESET WHCU BITE, IAW FIM 30-41/801. WHCU SYSTEM TEST NORMAL, IAW AMM 30-41-11-710-801. OPERATED WINDOW HEAT 30 MINUTES, NO FAULTS. REPLACED WHCU M323, OPS TEST GOOD, IAW AMM 30-41-11-000-801, AND 30-41-11-400-801.