6.1-3
3
Voltage Checks
Component
Testing
Equipment rrequired:
Digital Volt/Ohm Meter
Procedure
Testing for voltage at any of the components is a relatively
easy procedure. The following illustrates how to check
voltage at some of the components used in the heater.
Be aware on the heater's electrical control system that black
and red color coded wires will carry high voltage (either 120
V.A.C. or 220 V.A.C.). All other wires will carry low voltage (24
V.A.C.). Use extreme care to prevent electrical shock.
First, set the function selector switch of the tester to “AC”
(alternating current). Check for voltage at either the ignition
module or the individual component. To test, place one of
your tester probes at the “hot” power supply terminal of the
component being tested and the other probe to a grounded
portion of the heater’s cabinet. (Normally, a sheet metal
screw on the cabinet will serve this purpose.) Or, place your
probes across the terminals of component being tested. The
following are some examples showing both procedures:
Checking ffor vvoltage ssupply tto m
motor ffrom m
module.
Apply a tester probe to the end of the black motor wire and
the other probe to ground. When the module is energized,
you will see approximately 120 volts readout on the meter
display. This verifies the module is supplying voltage and the
wiring between the module and the motor is in good
condition.
Checking ffor vvoltage ssupply tto iigniter ffrom
module.
Apply the probes to the female terminals in the plastic
connector at the end of the red igniter wires. The board will
send voltage to the igniter once the motor stops after
prepurge. Voltage (120 V.A.C. approximately) will appear for
17 seconds, thereby proving both control module and igniter
wires are working properly.
Checking ffor vvoltage ssupply tto ggas ccontrol vvalve
from tthe hhigh-llimit sswitch.
Apply one probe to female terminal at end of brown gas
control valve wire and the other to ground. You will see 24
volts appear, proving both the module, high-limit switch, and
their respective wires are in order.
August 1999
Warning
Electrical S
Shock H
Hazard
■
Troubleshooting may require the heater to be
connected to its electrical supply.
■
Do not directly touch exposed terminal
connections when checking voltage. Use only the
insulated probes of the voltage tester.
■
Failure to follow this warning may result in
electrical shock leading to personal injury.
Motor
Wire
Connector
Connector