What was found
CREW REPORTED A BURNT CHEMICAL ODOR ON BOARD - WORST TOWARD FIRST CLASS AREA. POSSIBLE CONTAMINATION BY GROUND AIR UNIT IN ABQ. MAINTENANCE TROUBLESHOT CABIN AIR QUALITY PER TASK CARD 26L00021001. COULD NOT DUPLICATE ODOR WITH INDIVIDUAL ENGINES AT HIGH POWER SETTINGS OR WITH APU BLEED. ORIGINAL CONTAMINATION ALSO BELIEVED TO BE FROM GROUND UNIT IN ABQ. REMOVED AND REPLACED CABIN AIR HEPA FILTERS PER TASK CARD 99L10021001. NO ODOR IN CABIN AT THIS TIME.