TC reported TIMS indicated Front DT car#1 set aircon fault. Unable to reset. Staff (BGB) checked an d confirmed Front DT car #1 set aircon, reset - ok. Car was cooling. ~~~~~ 3512 TC reported TIMS indicated A/C 1 faulty Unable to reset. Staff (BGB) confirmed 3512 A/C 1, reset - ok. Car was cooling.  3512 A/c 1 No fault code found on TIMS. Aircon page on TIMS show #3512 Aircon 1 status as VENT. No cooling light and no fault light lit up on Aircon 1 panel. Cooling light unable to lit up even after pressing reset button and tripping and resetting CPCB. Observed that Aircon 1 CCU unable to function, CCU trip immediately after train aux on. Used thong meter to measure CCU current. Current hit maximum of 22A before CCU tripped. Notification 2521099 raised for CCU replacement.  Jonathan Koh 45175 Notif 2521099 Name                              : Jonathan Date    Of    Occurrence          : 05/09/2023 Last    Service    Date           :   EMU/Equipment/Location            : 511/512 / CCU / 3512 A/C 1 Equipment Serial No. (if  any)    :   Description Of Fault/Cause        : Unable to start & function Measurements    ( if  any )       :   Required   Rectification          : Required C/O 3512- A/C 1, To measure if aircon shorted to ground and check on MCU operation.  3512 A/c 1-2 found CMOCR2 faulty. Checked connection between u/v/w wire and ground - OK.    u/v/w phase winding at around 1.4 ohm. Aircon 1-2 current measured at 35A. Aircon 1-2 u/v/w wire isolated and insulated. Found #3512 Aircon 1-1 short cycling. Freon pressure found at 15/110 psi (LP/HP). No leak found on CCU. Vaccummed system and charged freon up to 40/120 psi (LP/HP). Ops 30 raised to check evaporator for leak.  Ridzuan/Huzzaidi 45176 BSD: 3512 A/C 1-1 To Check Evaporator For Leak   Checked 3512 AC1-1 AHU unit found no leak. Double checked freon piping satis. Connection ok. No signs of freon leakage or anomalies. Done by: Haslan, Din. 18/9/2023