What was found
ENROUTE, THE FLIGHT ATTENDANT NOTIFIED US THERE WAS AN ELECTRICAL ODOR. THE ODOR WENT AWAY, A SHORT TIME LATER THE D FLIGHT ATTENDANT PASSED OUT. WE DECLARED AND EMERGENCY AND RAN CHECKLIST QRH E3.1. GROUNDED - YES. CHECKED SEAT ELECTRICAL BOXES FROM ROW 7-11 NO SMELL NOTED, BOTH SIDE OF AIRCRAFT. TURNED ON AFT GALLEY OVEN FOR HALF HOUR, NO SMELL NOTED. ACCOMPLISHED AFT DOOR AREA HEATER OPERATIONAL CHECK, REF B737-900 AMM 21-45-00-700-802, OPS CHECK NORMAL. REMOVED AND REPLACED RECIRCULATION AIR FILTERS, REF B737-900 AMM 21-25-01-400-801. ACCOMPLISHED CONDITIONAL INSPECTION CABIN ODOR, REF B737-900 AMM 05-51-00. NO SMELLS NOTED.