Malfunction of
discharge
temperature
sensor
Check if the
control wire of outdoor fan motor is
connected on the outdoor
mainboard correctly
Replace the
outdoor fan motor and then
restart the unit to see if there still
is malfunction of outdoor fan
motor
Correctly connect the
control wire of fan motor
on the mainboard
Operate the unit with
the new motor
Replace the
outdoor
mainboard
Yes
No
No
Yes
3.4.21 ―H7‖ Driver Out-of-Step Protection
Error display: ODU mainboard, IDU wired control and IDU receiver light board will display H7
Error judgment condition and method:
During operation, it can‘t detect the rotor position and stops output. Or the actual running speed differs too
much from the set running speed. In each case, compressor runs out of step and system stops for protection.
Possible reason:
■Compressor 3-phase wire connection is lack of phase or phased-reversed.
■Compressor phase wire connection is bad.
■System is blocked, short of refrigerant or compressor oil.
■Drive board IPM module is damaged.
■Drive board compressor current sampling circuit element is damaged or drive chip current sampling AD terminal
is abnormal.
■Compressor is damaged.
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