What was found
AIRCRAFT 385 ATB, RETURNED TO DEPARTURE DUE TO NR 1 ENGINE AIR EXCHANGER FAULT. TROUBLESHOT IAW TSM 79-20-00-810-809A, FADEC SYSTEM TEST OK, GROUND CHECK WITH NO ECAM MESSAGES, RAN NR 1 AND 2 ENGINES ON THE GROUND, ALSO NO ECAM MESSAGES APPEARED. ACFT RETURNED TO SERVICE.