GREE U-Match 6 SERIES UNIT SERVICE MANUAL
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Troubleshooting:
3.4.16 “U7” 4–Way Valve Switch-Over Error
Error display:
ODU mainboard, IDU wired controller and IDU receiver light board will display U7
Possible reason:
■Voltage is abnormal. For example, low voltage will cause abnormal direction change of the 4-way
valve.
■Pilot valve holder hole or the capillary tube is blocked, which has caused small flow or no flow.
■Capillary tube is blocked when connecting to the pilot valve or main valve.
■Coil is not power-connected, or is open-circuited. Voltage is low, or the contact between turns or
terminals is bad.
■The stainless steel cover of pilot valve is damaged, or the steel core is stuck, or the spring is not
elastic.
■Insert block is bent or not elastic, so the little slide cannot get in place.
■When adding refrigerant, the little slide is over-running and can’t spring back.
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