GREE U-Match 5 SERIES UNIT SERVICE MANUAL
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3.4.25 ―U7‖ 4–Way Valve Switch-Over Error
Error display: ODU mainboard, IDU wired control and IDU receiver light board will display U7
Error judgment condition and method:
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.
Troubleshooting：
Check whether the terminals of coil is well
connected and the4-way valve can be energized.
Check whether the power voltage is normal. Low
pressure will lead to abnormal direction change
U7 4–way valve switch-over error
Return to normal.
Use normal voltage.
Replace the 4-way valve
YES
NO
NO
YES
3.4.26 ―P0‖ Driver Reset Protection
Error display: ODU mainboard, IDU wired control and IDU receiver light board will display P0
Error judgment condition and method:
Drive board chip resets and starts initialization. After the drive board is energized for 5s, it detects that the
chip resets again. In this case, it can be judged as drive chip reset protection.
Possible reason:
■3.3V drive chip supply voltage drop.
■TRST lead of JTAG programming is interrupted.
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