TC reported TIMS shows intermittent 'AirDryer' fault in car 3641. Train performance all ok. ~~~~~ 3642 TC reported TIMS shows intermittent 'Air  Dryer' fault in  3641. Train performance all ok. CE checked: T244-3641 intermittent Air Dryer Fault. Fault Code 704. Train due SC to UPD.  3641 FC 704. Replaced #3641 with new air dryer & micro mesh filter. Security check - OK. Function test air dryer operation, able to purge & change-over every 2 mins. Air compressor cut-in at 8.5 bar & cut-out at 10.5 bar. Air leak test = 0.4 bar/5 mins.  Alif/Sugu/Anand/Chan SW 45125 #3641 Air Dryer S/N : OLD : 015-125-38 NEW : 3515460317