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Continuity Checks
Component
Testing
Continuity C
Checks
Equipment rrequired:
Digital Volt/Ohm Meter
Explanation:
In a continuity test, you simply want to determine whether or
not an electrical pathway exists through a component. For
these tests, it is important that the probes of the multimeter
make good contact with the part being tested. They should
touch bare metal or wire, not insulation, paint, or dirt.
Alligator clips make firmer contact than needle probes, use
them where possible.
The components which exhibit good continuity within the
electrical circuit also provide a resistance to the flow of
electricity. The resistance is measured in ohms and will be
displayed on the meter. You do not need to remove the
components to check for continuity. Also, manipulate wires
to see if they are loose to help uncover poor connections or
other electrical interruptions. The following illustrates how to
check for continuity for some of the components used in the
heater.
Attention
Make sure that the heater is disconnected from its electrical
source before conducting this procedure. Failure to do so
will result in damage to your meter.
Procedure
First, set your meter to the continuity scale (if provided) or
the ohm(s) scale. Place the tester probes on the terminals
of the component being tested. If your meter has an audible
continuity feature you will hear a “ringing” sound in addition
to seeing a read out in ohms. Examples of checking for
continuity on several components are shown.
Typically, components which show an open circuit and are
not in proper working order will exhibit an “overload” readout
on the display of the multimeter. These components should
be replaced. However, some components such as an air
proving switch have a set of normally open contacts. To
verify proper operation, the switch arm needs to be pushed
so the contacts are engaged. At this point an ohm reading
should appear.
August 1999
High LLimit S
Switch
Air-PProving S
Switch
Hot S
Surface IIgniter
Some components, such as an igniter, have a much larger
amount of resistance to the flow of electricity. The ohm read
out will be much greater on the igniter than on some other
components such as an air-proving switch or high-limit
switch. Continuity through the igniter indicates that it is
good.
To check for proper thermostat operation, connect the
testing probe to the end of the thermostat cord set leads that
normally connect to the heater. When the thermostat
contacts are open, the meter will show an open circuit.
When the thermostat is adjusted to call for heat, the
contacts should close and you will see an ohm readout
Igniter
Connector
6.2-1
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