Lennox SL280DFNV Series Unit Information page 23

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 14
Ohm Meter Range
Scale
In Words
2M two megohm - two
million ohms
200k two hundred kilohm
- two hundred
thousand ohms
20k twenty kilohm --
twenty thousand
ohms
2k two kilohm -- two
thousand ohms
200 two hundred ohm
FIGURE 10
Measurement Range
ohms
0 - 2,000,000
0 - 200,000
0-20,000
0 - 2,000
0 - 200
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, re-
place the motor and control module. If the resistance
to ground is >100k, the motor windings are fine. Pro-
ceed to Test B.
Use an ohmmeter to measure the motor phase-to-phase
resistance by checking these combinations of the the 3-pin
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
should be less than 20 ohms.
2 - Each lead-to-lead resistance should be the same.
If the measured resistance is greater than 20 ohms, re-
place the motor and control module.
Page 23
TEST A
Test A
FIGURE 11
TEST B
Test B
FIGURE 12