Troubleshooting Motor Windings; Heating Components; Ignitor/Flame Sensor; Gas Valve - Lennox EL296DF045XV36B Unit Information

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
Flame Signal in Microamps
Measurement Range
Scale
in words
two megohm -- two
2M
million ohms
two hundred kilohm
-- two hundred thou­
200k
sand ohms
twenty kilohm --
twenty thousand
20k
ohms
two kilohm -- two
2k
thousand ohms
200 two hundred ohm
FIGURE 10
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.
Test A
FIGURE 11
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
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.
ohms
0-2,000,000
0-200,000
0-20,000
C- Heating Components
0-2,000
1. Ignitor
The SureLight
0-200
nitor longevity is enhanced by controlling voltage to the ig­
nitor. The integrated control provides a regulated 120 volts
to the ignitor for a consistent ignition and long ignitor life.
Ohm value should be 39 to 70. See figure 13 for ignitor
location and figure 14 for ignitor check out.
NOTE - The EL296DFV(X) furnace contains electronic
components that are polarity sensitive. Make sure that the
furnace is wired correctly and is properly grounded.
2. Flame Sensor
A flame sensor is located on the left side of the burner sup­
port. See figure 13. The sensor tip protrudes into the flame
envelope of the left-most burner. The sensor can be re­
moved for service without removing any part of the burn­
ers. During operation, flame is sensed by current passed
through the flame and sensing electrode. The SureLight
control allows the gas valve to remain open as long as
flame signal is sensed. To check flame sense signal use the
push-button found on the integrated control and go to Field
Test Mode. The menu will display the flame signal. See
table 15 for flame signal.

3. Gas Valve

The valve (figure 51) is internally redundant to assure safe­
ty shut-off. If the gas valve must be replaced, the same type
valve must be used.
24VAC terminals and gas control knob are located on the
valve. A wire harness connects the terminals from the gas
valve to the electronic ignition control. 24V applied to the termi­
nals energizes the valve.
Inlet and outlet pressure taps are located on the valve. A regu­
lator adjustment screw is located on the valve.
LPG change over kits are available from Lennox. Kits include
burner orifices and a gas valve.
Page 26
should be less than 20 ohms.
Test B
FIGURE 12
®
ignitor is made of durable silicon nitride. Ig­
TABLE 15
Flame Signal in Microamps
Normal Low
2.6 or greater 2.5 or less
Drop Out
1.1