What was found
DURING TAKEOFF, A LOUD SOUND OF RUSHING AIR & CABIN PRESSURIZING RAPIDLY. ACCOMPANIED BY A STRONG BURNING ODOR. ANNUNCIATOR WITH FLASHING MASTER CAUTION ILLUMINATED BUT WENT OUT. TROUBLESHOT AND VERIFIED ODOR IN COCKPIT & CABIN. PERFORMED ENGINE RUNS & OPS CHECKED AIR CONDITIONING SYS. INSPECTED ACM, NO DEFECTS NOTED. BURNING ODOR IN COCKPIT BUT NOT IN CABIN. SHUT ENGINES DOWN & WITH THE APU BLEED AIR & ODOR PRESENT IN COCKPIT. ODOR IS COMING FROM THE LT GLARE SHIELD FAN AREA. VERIFIED PFD 1 MODE SELECTOR CONTROLLER TO BE THE SOURCE OF ODOR. REMOVED AND REPLACED THE LT MODE SELECTOR. OPS CHECKED GOOD IAW MM 34-25-01. COMPLIED WITH HIGH POWER ENG RUNS. NO DEFECTS NOTED & NO CAS MESSAGES NOTED.