Inside and outside of the air-conditioning compressor and fan contactors are used to control the phase and neutral line N R for the control circuit to provide 220V AC. Measured at the outlet end of the air switch R, S, T three phases should be infinite resistance, the measured R T phase alternating resistance 3Ω, and no signs of a short circuit was suspected contacts bad. Contactor is still detected in the two groups switched power failure, resulting in a boot on the phase compressor starts, the starting current form larger replacement after troubleshooting the same model contactor.XDsservice manual download site