Check SiUS121630EA194 Service Diagnosis8.5 Electronic Expansion Valve CheckCheck No.12 Conduct the following to check the electronic expansion valve (EV).1. Check if the EV connector is correctly inserted in the PCB. Match the EV unit number and theconnector number.2. Turn the power off and on again, and check if all the EVs generate a latching sound.3. If any of the EVs does not generate a latching sound in the above step 2, disconnect thatconnector and check the continuity using a multimeter.Check the continuity between the pins 5 - 1, 5 - 2, 5 - 3, 5 - 4. If there is no continuity between thepins, the EV coil is faulty.4. If no EV generates a latching sound in the above step 2, the outdoor unit PCB is faulty.5. If the continuity is confirmed in the above step 3, mount a good coil (which generated a latchingsound) in the EV unit that did not generate a latching sound, and check if that EV generates alatching sound.∗If a latching sound is generated, the outdoor unit PCB is faulty.∗If a latching sound is not generated, the EV unit is faulty.Note: Please note that the latching sound varies depending on the valve type.If the system keeps operating with a defective electronic expansion valve, the following problemmay occur.Valve openingposition Possible problem Check methodOpen Cooling: Flowing noise of refrigerant in theunit which is not in operation Water leakage at the unit which isnot in operation Operation half due to anti-icingfunctionReset power supply and conduct cooling operationunit by unit.Heating: Flowing noise of refrigerant in theunit which is not in operation The unit does not heat the room.Close Cooling: The problem unit does not coolthe room. Only the problem unit is inoperation, the unit starts pumpdown.(The low pressure of the unitbecomes vacuum.) Abnormal discharge pipetemperatureReset power supply and conduct cooling operationunit by unit.Heating: Refrigerant shortage due tostagnation of liquid refrigerantinside the faulty indoor unit The unit does not heat the room. Abnormal discharge pipetemperatureCheck the liquid pipe temperatureof no-operation unit.YES(R16019)NO The EV is notdefective.Replace the EVof the room.Almost the sameas the outdoortemperature?Check the low pressure.(R16020)YESNOReplace the EVof the room.The EV is notdefective.Does the pressurebecome into vacuumzone?
