RESISTIVE AND INDUCTIVE LOAD MEASUREMENT PROCEDURES

StepExpected Result/Action
NOTE: Steps 1 and 2 test resistive loads. Resistive loads include resistors,
electric crankcase heaters, electric heater elements, and similar devices.
1. Turn power off, then discharge all capacitors in the circuit. Disconnect at least
one lead of the resistive load from the circuit.
Power is off and the resistive load is isolated from the circuit in preparation for
the resistance measurement.
2. Set up the VOM/DMM to measure resistance. Select a resistance range that is
higher than the resistance expected. If unknown, start at the highest range
then work your way down to a lower range when making the measurement.
Connect the VOM/DMM across the resistive load as shown in Figure SP-8-7,
View A. Measure the resistance.
If the VOM/DMM shows a normal resistance reading, as specified by the
manufacturer, the resistive load is good.
If the VOM/DMM shows an infinite resistance reading, the resistive load is open;
if it shows a zero reading, the resistive load is shorted. In either case, the resistive
load is bad and should be replaced.
NOTE: Steps 3 and 4 test inductive loads. Inductive loads include relay and
contactor coils, control transformer windings, solenoids, and gas valve
coils. Tests for compressor motors and other motors, which are also
inductive loads, are covered in Service Procedure SP-9 (compressor
motors) and SP-10 (other motors).
3. Turn power off, then discharge all capacitors in the circuit. Disconnect at least
one lead of the inductive load from the circuit.
Power is off and the inductive load is isolated from the circuit in preparation for
the resistance measurement.
4. Set up the VOM/DMM to measure resistance. Select a resistance range that is
higher than the resistance expected. If unknown, start at the highest range
then work your way down to a lower range when making the measurement.
Connect the VOM/DMM across the inductive load as shown in Figure SP-8-7,
View B. Measure the resistance.
If the VOM/DMM indicates the normal resistance reading, as specified by the
manufacturer, the inductive load is good.
If the VOM/DMM indicates an infinite resistance reading, the inductive load is
open; if it indicates a zero resistance reading, the inductive load is shorted. In
either case, the inductive load is bad and should be replaced.

pic1 98 RESISTIVE AND INDUCTIVE LOAD MEASUREMENT PROCEDURES


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