TC reported unusual noise coming from car front DT. Staff(NOV) checked and confirmed at car front DTnoise from train motor. Staff(NOV) feedback sound could be heard from platform. TC reported APS fault converter local o ~~~~~ 3547 checked/found air compressor operation very noisy. Found FC 719 (Air compressor motor over current), causing APS fault. OPS 20 raised to c/o air compressor.  Hanafi/Chan SW. 13/07/2021.  3547 air compressor replaced. Function test air compressor - OK. Performed pneumatic system check as per checklist. (Refer to attached checklist for results). #3547 Air Compressor S/N : OLD : 120A-0003. NEW : 120F-3395.  Chan GF/Alan/Shafie. 13/07/2021.