Problem
Unintentional ground.
Pump does not start
and overload heaters
3-phase motor winding failure.
trip.
Obstructed impeller or volute.
Pump operates with
control panel selector
switch in Hand position
Control circuits malfunctioning.
but does not operate in
Auto position.
Pump is airlocked.
Lower float switch control hung-up in the closed
position.
Control panel selector switch in Hand position.
Pump runs, but does
not turn off.
Float switch unable to move to the PUMP OFF
position due to interference with the side of
basin or other obstruction.
Control panel failure.
Defective float switch.
Discharge is blocked or restricted.
Check valve is stuck closed or installed backward.
Gate or ball valve is closed.
Total head (lift height) is beyond pump's
capability.
Pump runs or hums, but
Obstructed impeller or volute.
does not pump.
Pump is airlocked.
Capacitor failure in control panel.
Stuck/defective motor contactor in control
panel.
Pump is not seated correctly in guide rail base.
– 10 –
Table 3. Troubleshooting Matrix (continued)
Possible Cause
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Corrective Action
Turn off power and check motor leads for possible
ground.
Check resistance of motor windings. All three phases
should have the same reading.
Remove obstruction.
Check float level control or the alternator relay for issues.
Check control panel.
Turn pump off and let set for several minutes, then
restart.
Check in basin that float switch has free movement.
Set selector switch to Auto position.
Position the pump or float switch so that it has adequate
clearance for free movement.
Check control panel.
Replace float switch.
Check the discharge line for foreign material, including
ice if the discharge line passes through or into cold areas.
Remove check valve(s) and examine for freedom of
operation and proper installation.
Open gate or ball valve.
Route piping to a lower level. If not possible, a larger
pump may be required. Consult Liberty Pumps.
Remove obstruction.
Turn pump off and let set for several minutes, then
restart.
Add baffle to reduce trapped air bubbles.
Check capacitors and replace if needed.
Replace motor contactor.
Lift pump and re-position.
5647000K