What was found
LEFT FWD WINDOW HEAT OVERHEAT LIGHT ILLUMINATED WITH POWER OFF, ON THE GROUND. NOT PRESENT IN FLIGHT. ACFT GROUNDED. VERIFIED FAULT WITH SWITCH ON, NO OVERHEAT WITH SWITCH OFF, OVERHEAT. CYCLED POWER, ACCOMPLISHED HISTORY BITE TEST FOR LT FWD WHCU, FAULTED P5-9 CONTROL POWER. ACCOMPLISHED WINDOW/PITOT HEAT MODULE (P5-9) INSTALLATION TEST, TEST PASSED IAW AMM 30-41-41-400-801. NO FAULTS, IAW AMM 30-41-11-710-801.