What was found
AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANT REPORT UNUSUAL ACRID AND BURNING ODOR SMELL NEAR MID CABIN WITH PACKS RUNNING. COMPLETED J/C 08L00021001, WHILE TROUBLESHOOTING FOUND THAT SMELL WOULD GET STRONGER WITH RIGHT HAND RECIRCULATION FAN ON, AND SUBSIDE WHEN RIGHT HAND RECIRCULATION FAN WAS OFF. WHILE RUNNING PACKS WITH NO RECIRCULATION FANS ON SMELL WOULD SUBSIDE. REMOVED AND REPLACED RIGHT HAND RECIRCULATION FAN (AALA202605203519), PER AMM 21-25-02. OPS CHECK GOOD. ALSO, REMOVED AND REPLACED BOTH CABIN AIR HEPA FILTERS (AALA202605208192) (AALA202605201060), PER AMM 21-25-01. RAN PACKS FOR OVER TWO HOURS WITH RECIRCULATION FANS ON, NO SMELL NOTED.