Mars Comfort-Aire Century VCD-SA Series Service Manual page 158

Service Manual - VCDxxSA
8.4 4-way Valve Check
1. Power on, use a digital tester to measure the voltage, when the unit operates in cooling, it is 0V. When the unit
operates in heating, it is about 230VAC.
If the value of the voltage is not in the range, the PCB must have problems and need to be replaced.
2 Turn off the power, use a digital tester to measure the resistance. The value should be 1.8~2.5 KΩ.
 Troubleshooting 