TC 120
682.98767.00 • 10/04/2018
40
Chapter 7: Troubleshooting
7-1 Introduction
The utmost in safety precautions should be observed at all times when working on or around
the machine and the electrical components. All normal trouble-shooting must be
accomplished with the power off, circuit breakers turned off, and with the machine tagged as
out of service.
The use of good quality test equipment cannot be over-emphasized when troubleshooting is
indicated. Use a good ammeter that can measure at least twice the AC and DC current that
can be encountered for the machine. Be sure that the voltmeter has at least minimum
impedance of 5,000 OHMS-per-volt on AC and 20,000 OHMS-per-volt on DC scales.
Popular combination meters, VOM and VTVM can be selected to provide the necessary
functions.
Before making haphazard substitutions and repairs when electrical components have
malfunctioned, we recommend that you check the associated circuitry and assemblies for
other defective devices and root causes of the problem. It is common to replace the obviously
damaged component without actually locating the real cause of the trouble. Such hasty
substitutions will only destroy the new component. Refer to wiring diagrams and schematics.
Locating mechanical problems, should they occur, is relatively straightforward. When
necessary, refer to the parts catalog section.
Problem
Possible Cause
Possible Remedy
Unit does not turn
on.
No power.
Check main disconnect, fuses,
wiring, and power lead to unit.
Wrong voltage supplied to
unit.
Voltage must be within plus or
minus 10% of nameplate rating.
Defective controller.
Replace.
Control circuit fuse blown.
Replace.
Defective control transformer.
Check transformer.
Unit does not run.
Broken or loose wire in pump
motor control circuit.
Locate and repair.
Pump motor contactor holding
coil is open.
Repair or replace.
Low water pressure light on.
Check for at least 16 psig (110
kPa/1.1 bar) water pressure on
WATER IN
or
CITY WATER
MAKEUP
.
Water supply to unit is turned
off.
Open water supply.
Pump overload light on.
Reset and test each leg for
balanced amp draws.