What was found
(CAN) WHILE IN CRUISE, NR 1 WINDSHIELD HEAT SYS FAILED, FLIGHT CREW CYCLED THE IPS, ICE PROTECTION SYSTEM AND THE WINDSHIELD HEAT RESET. IN ANOTHER 5 MINUTES, THE FLIGHT CREW NOTICED AN ACRID BURNING ODOR. IPS SYS AND HEATERS WERE SWITCHED OFF, THE ODOR IMMEDIATELLY DISAPPEARED. UPON LANDING, MAINTENANCE PERSONNEL DISPATCHED, DEACTIVATE THE IPS SYSTEM, INCLUDING THE AC GENERATOR, ACFT DISPATCHED AND RETURNED TO BASE.