Lennox EL296UHVX Series Unit Information page 44

Troubleshooting Motor Windings
Ensure that motor windings are not damaged by perform­
ing the following tests:
NOTE - If your ohm meter is not an auto-ranging type, set it
to the highest ohm scale (100k ohms or greater) before
performing tests.
TABLE 15
Ohm Meter Range
Measurement Range
Scale
in words
two megohm -- two
2M
million ohms
two hundred kilohm
200k -- two hundred thou­
sand ohms
twenty kilohm --
twenty thousand
20k
ohms
two kilohm -- two
2k
thousand ohms
200 two hundred ohm
FIGURE 11
TEST A
Measure the resistance between each of the three motor
leads (3-pin plug) and the unpainted part of the end shield.
If the winding resistance to ground is <100k
ohms, replace the motor and control module. If
the resistance to ground is >100k, the motor
windings are fine. Proceed to Test B.
ohms
0-2,000,000
Use an ohmmeter to measure the motor phase-to-phase
resistance by checking these combinations of the the 3-pin
0-200,000
motor plug. For the purpose of this test, start at either end of
the connector as lead 1.
1 - The lead-to-lead resistance across any two leads
0-20,000
2 - Each lead-to-lead resistance should be the same.
0-2,000
If the measured resistance is greater than 20 ohms, re­
0-200 place the motor and control module.
Removed the three blower leads from the blower drive. see
TEST A. If ohms to ground shows resistance replace mo­
tor. If the circuit is open move to test B and table below for
acceptable resistance. If ohm reading is met motor has
passed. If the motor passes both test A and B and the shaft
spins freely by hand, replace the blower drive.
Motor HP
1/2
3/4
1
Page 44
Test A
FIGURE 12
TEST B
should be less than 20 ohms.
Test B
FIGURE 13
Models with the Lennox Blower Drive
Ohm reading
7.6 + .76
6.3 + .63
4.7 + .47