TC reported air-con fault at rear M2 car#2 set. Unable to reset. Staff(BGB) checked and confirmed f ault. Unable to reset. Car was cooling. ~~~~~ 2613 TC reported A/C 2 fault Unable to reset. Staff(BGB) confirmed fault Unable to reset. Car was cooling. CE checked: 2613 #2 AC not Working. AC Warm.Temp 26.4*C.  2613 A/c 2-1 FC 618 (Freon pressure low). Found A/c 2-1 low pressure pipe coupling slight oil seepage. Discharged/vacuum A/c 2-1 CCU.    Charged freon to LP = 50psi, HP = 140psi. Performed leak test on coupling - OK. Re-tightened coupling as preventive measure. Function test A/c cut-in/out operation - OK. Monitor for 1 hour, holding pressure at LP = 50psi - OK.  Aliff/Anand/Sugu/Chan SW 45155