Servend MD 150, Installation & Service Manual

Page: 57 / 64

Installation and Service Manual
57
PROBLEM POSSIBLE CAUSE CORRECTIVE ACTION
Pump motor does not
pump. Black and/or red probe shorted
Problem with motor or motor wiring
Problem with Liquid Level Control
Board.
Water pressure from water source is
not high enough.
Remove probes and bend straight or replace with new
probe(s)
Check line voltage first. Check AC voltage across
load terminals on Liquid Level Control. If voltage is
120 plus or minus 10%, replace motor or motor wiring.
Check line voltage first. If AC voltage across load
terminals is not 120 plus or minus 10%, replace the
Liquid Level Control Board.
Verify water pressure leading into pump inlet is 40 psi
minimum with pump running.
Pump will not run but
tank appears to be
always full.
Common Lead (Green) shorted out to
Red wire (High Probe) Verify Green and Red wires are not touching.
Pump will not run but
tank level appears to
be below start level.
Common Lead (Green) shorted out to
Black wire (Low Probe) Verify Green and Black wires are not touching.
Pump motor does not
shut off. Problem with Liquid Level Control
Board
Probe Harness Connection may be
open.
Water may not be reaching top probe
in carb tank.
High Lead (Red) open or not
connected.
Common lead (Green) open or not
connected.
Short the "H & L" terminals on the Liquid Level Control
Board. If motor does not shut off, replace Liquid Level
Control Board.
Verify connections are good or replace the wiring
harness.
Verify tank is not filled with CO
2
or air by pulling relief
valve up and letting air escape until water begins
coming out.
Verify Red lead wire is connected from tank to unit.
Verify Green lead wire is connected from tank to unit.
Pump motor
intermittent Problem with probe or probe harness.
Problem with motor or motor wiring.
Check motor and motor wires by removing red and
black wires from the Liquid Level Control Board. If
okay, short "H & L" terminal on Liquid Level Control
Board. If motor stays off, verify probes and bend
straight or replace. Verify with meter.
Measure AC voltage across load terminals on Liquid
Level Control Board. If line voltage is 120 plus or
minus 10% replace motor or motor wiring.
TROUBLESHOOTING
PUMP