York EVHC 09 DSAAAR Service Manual page 47

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