What was found
L FWD WINDOW HEAT LIGHT ILLUMINATED, EXTINGUISHED AFTER QRH PROC. GROUNDED - YES. AFTER A/C RETURN TO GATE, OBSERVED OVERHEAT LIGHT ON FOR LEFT FORWARD. ACCOMPLISHED B737-9 IFIM 30-41-00-810-828. RESISTANCE CK FOR PRIMARY SENSOR SHOWS OPEN, SPARE SENSOR CKED NML & HEAT FILM CKED GOOD REF B737-9 WDM 30-41-11. DUE TO OPERATIONAL NEEDS WHCU OVERRIDE MODE ACTIVATED TO SPARE SENSOR REF B737-9 AMM 30-41-11-440-801 LEFT FWD WINDOW HEAT OPS NML.