78 OM Centrif Micro ΙΙ-5
Table 34, During starting, motor rotates but does not reach full speed
Condition Cause Solution
Fault Displayed. Fault Occurred.
See fault code troubleshooting table for
more details.
Motor loading too high and/or
current not dropping below
175% FLA indicating that the
motor has not come up to
speed.
Reduce load on motor during starting.
Display shows Accel or
Run.
Abnormally low line voltage. Fix cause of low line voltage.
Motor Hums before turning Initial current to low Increase initial current
Table 35, Motor stops unexpectedly while running
Condition Cause Solution
Fault Displayed. Fault Occurred.
See fault code troubleshooting table for
more details.
Control voltage absent.
Check for proper control voltage input.
Verify wiring and fuses.
Display Blank, Heartbeat
LED on D3 board not
blinking.
D3 control board problem. Consult McQuay Service.
Table 36, Metering incorrect
Condition Cause Solution
Loose connections.
Shut off all power and check all
connections.
Load actually not steady.
Verify that the load is actually steady
and that there are not mechanical
issues.
Motor Current or Voltage
meters fluctuating with
steady load.
Other equipment on same
power feed causing power
fluctuations and/or distortion.
Fix cause of power fluctuations and/or
distortion.
Table 37, Other Situations
Condition Cause Solution
If input phasing correct, exchange any
two output wires.
Motor Rotates in Wrong
Direction
Phasing incorrect
If input phasing incorrect, exchange any
two input wires.
Erratic Operation Loose connections
Shut off all power and check all
connections.
Motor overloaded Reduce motor load.
Too many starts per hour
Increase chiller LWT setpoint
deadband.
High ambient temperature
Reduce ambient temperature or provide
for better cooling.
Acceleration time too long Reduce starting load.
Motor Overheats
Motor cooling
obstructed/damaged
Remove cooling air obstructions. Check
motor cooling fan.
Continued on the next page.
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