TC reported air-con fault. Unable to reset. Staff(AMK) checked and confirmed that RDT car set #2 air -con faulty. Unable to reset . Car was warm. Train was refor med with a PM peak withdrawal train. TC reported air-con fau ~~~~~ To follow up and rectify.  3710 replaced MSPR preventively. Swapped PSK & KR from #3710 to #1710 for monitoring. Checked PSK, KR, MSPR & TRSK1 coil & contacts - Satis. APS power test - Passed.  Lee JC 44844 3710 TC reported air-con fault Unable to reset. Staff(AMK) confirmed 3710 A/C 2 faulty Unable to reset. Car was warm. Train was reformed with a PM peak withdrawal train.  3710 checked on TIMS & found no APS voltage. Found U/F APS cover limit s/w not activated. Re-aligned the limit S/w & function test - OK. APS voltage 110v was present.    #3710 A/C 1-1 LP = 35 psi, HP = 120 psi, running AMP = 9.7 amp. #3710 A/c 1-2 LP = 38 psi, HP = 115 psi, running AMP = 9.5 amp. #3710 A/c 2-1 LP = 36 psi, HP = 120 psi, running AMP = 9.4 amp. #3710 A/c 2-2 LP = 38 psi, HP = 115 psi, running AMP = 9.8 amp. Checked A/c cut-in/out operation - OK. Saloon temp. 23*C. Monitor 2 hours, no fault recurred & no freon leakage found. As preventive measure, swapped APS control board #3710 to #1710. Function test - OK. During depot shunting, fault recurred. OPS 20 raised to follow-up.  Sarma 44842 Current APS Control Board S/N : #3710 - FB0001446-04H #1710 - FB0001446-07H