York DHP30NWB21SDCP30NWB21SDHP36NWB21SDCP36NWB21S Service Manual page 60

(5) Out of step diagnosis for the compressor (AP1 hereinafter refers to the control board of the outdoor unit)
Mainly detect:
Whether the system pressure is too high?
Whether the input voltage is too low?
Fault diagnosis process:
Out of step occurs once the
unit is powered on.
Is stop time of the
compressor longer than
Are the wires for the compressor connected
correctly? Is connection sequence right?
Is the connection made in clockwise
Connect the
wires correctly
Replace the control
If the fault is eliminated?
53
3 minutes?
direction?
panel AP1
Replace the
compressor
End
Out of step occurs in
operation
Is the outdoor fan working
normally?
Is the outdoor unit blocked Remove foreign
by foreign objects? objects
Replace the
control panel AP1
If the fault is eliminated?
Replace the
compressor
End
Using an Amp meter set to
Ohms, measure between
any two end terminals and
ensure a reading less than 1
Kohms
Replace the
outdoor fan