What was found
BTB - CAN NOT CONTROL FWD CABIN HEAT ACFT RETURNING TO THE GATE. COND TRIM AIR SYSTEM FAULT FWD CABIN TRIM VALVE ECAM // REMOVED AND REPLACED FWD CABIN TRIM VALVE (12HK) PER AMM 21-63-51. OPS CHECK GOOD, RAN BOTH ENGINES AT IDLE FOR FIVE MINUTES, NO FAULTS NOTED. OK FOR SERVICE