What was found
FLIGHT 2906, CREW REPORTED DURING PUSHBACK THERE WAS A SUDDEN DECREASE OF AIR FLOW FROM GASPERS WHILE ON APU, TRIED TO START ENGINES AND TAXI BUT PROBLEM PERSISTED IN AUTO AND MANUAL. A PASSENGER IN ROW 4 REPORTED A BURNING ODOR ON TAXI. IN COCKPIT TEMP 37C CABIN REACHED 30C. AIRCRAFT REMOVED FROM SERVICE. FOUND RECIRCULATION FAN 1 AND 2 FAILED REMOVED AND REPLACED NR 1 AND 2 RECIRCULATION FANS IAW AMM 21-24-01. OPS CHECKED GOOD IAW AMM TASK 21-20-00-700-801-A. AIRCRAFT RETURNED TO SERVICE.