(2) IPM Protection, Out-of-step Fault, Compressor Phase Overcurrent (AP1 below refers to the outdoor
control panel)
Is the connection between control panel AP1 and compressor COMP secure? Loose? Is the connection in correct
order?
Is the voltage input of the machine within normal range? (Use AC voltmeter to measure the voltage between terminal
L and N on the
wiring board XT)
Is the compressor coil resistance normal? Is the insulation of compressor coil against the copper tube in good
condition?
Is the working load of the machine too high? Is the radiation good?
Is the charge volume of refrigerant correct?
Fault diagnosis process:
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