Stock change over of train was arranged3685,at JUR due to wet floor in car 3685.Staff(SOM & MSP) feedb ack were unable to locate source of water. Water was seen insaloon car near to driving cab of car 3685. ~~~~~ Water was seen in saloon car near to driving cab of 3685.  3685 checked #1E ceiling panel & return air grille for water seepage/stain - OK. Checked cab A/c for water leaking - OK. Checked cab A/c & saloon A/c operation - OK. Checked #1E air flow - OK. Replaced cab A/c filter as it was dirty.  Ridzuan. 16/11/2020.