What was found
LEFT SIDE WINDOW OVERHEAT ILLUMINATED AT CRUISE. TURNED OFF FOR 5 MINUTES. TURNED BACK ON AND OVERHEAT ILLUMINATED AGAIN. GROUNDED - YES. WHCU SHOWS SENSOR FAULT HISTORY. CHANGED WIRES FROM PRIMARY SENSOR TO THE SPARE SENSOR REF B737-900 AMM TASK 30-41-00-420-801. PERFORMED WINDOW HEAT SYSTEM OPS TEST AND WHCU BITE PROCEDURE, OPS CK'D GOOD AND NO ACTIVE FAULTS REF AMM 30-41-00-710-801 AND B737-900 FIM TASK 30-41 #801.