Additional Indoor Blower Motor Troubleshooting; Typical Digital Multimeter; Module Test; Motor Test - Lennox CBX32MV-018/024 Manual

INDOOR BLOWER MOTOR (B3) CONTROL
TROUBLESHOOTING (EMERSON)
1. Disconnect three-wire harness from motor control
module.
A If the plug terminals inside the module are
damaged.
B If terminals are not damaged, proceed to next step.
2. Inspect the negative temperature coefficient (NTC)
thermistor (see figure 33) for any cracks or breakage.
A If damaged, replace control.
B If no damage is detected, proceed to next step.
3. Check the capacitors for any damage. Inspect for:
A Bulging or swelling caps. If caps are bulging or
swollen, replace control.
B If no damage is detected, proceed to next step.
4. Check resistance between each of the three pins on the
control module jack (see figure 33). Resistance
between any two terminals should be greater than 100
K ohms.
A If resistance is less than 100 K ohms, replace
control.
B If no damage is detected, proceed to next step.
NOTE - If your ohm meter is not an auto-ranging type,
please set it to the highest ohm scale (100 K ohms or
greater).
Measurement range in
Scale
words
two megohm-two million
2 M
ohms
two hundred kilo-ohm-two
200 K
hundred thousand ohms
twenty kilo-ohm-twenty
20 K
thousand ohms
two kilo-ohm two-thousand
2 K
ohms
200 two hundred ohms
Figure 32. Typical Digital Multimeter
CBX32MV
Additional Indoor Blower Motor (B3)
Troubleshooting
1. If motor shaft spins freely in both directions, proceed to
2. Check the motor to control harness for any damage.
ohms
3. Check resistance between each of the three-phase
0 - 2,000,000
0 - 200,000
0 - 20,000
0 - 2,000
0 - 200
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CONTROL MODULE
3-PIN JACK
NTC
THERMISTOR
Figure 33. Module Test (Emerson(
next step. If not, replace motor.
A If harness or terminals are damaged replace the
motor.
B If there is no damage, proceed to next step.
terminals in the motor harness as illustrated in figure
34. Resistance between any two contacts should be
equal. If resistance between any two contacts are not
equal, or if any resistance shows open or
short-circuited, replace the motor.
Figure 34. Motor Test (Emerson)
MOTOR 3-PIN
PLUG