What was found
LEFT FWD WINDOW HEAT OVERHEAT LIGHT ILLUMINATED ON FINAL APPROACH. GROUNDED - YES. (WHCU BITE PROCEDURE REF FIM 30-41 TASK 801 FAULT HISTORY SHOWS WHCU-LRU FAIL. PER B737-900 FIM 30-14 TASK 807, REQUIRES WHCU (M321) P/N 83000-27904, NIS @ LAX AS46962. AS REQ'D PER FIM TASK 30-41 TASK 807 STEP F. (2), R+R THE WHCU (M321) REF AMM 30-41-11, INSTALLATION TEST PASSED, A/C IS OK FOR SERVICE. PULLED THEN RESET 4 C/B'S.