Lennox EL297DFV Series Unit Information page 63

I- Proper Ground and Voltage
A poorly grounded furnace can contribute to premature
ignitor failure. Use the following procedure to check for
ground and voltage to the integrated control.
1 - Measure the AC voltage between Line Neutral
(spade terminals) and "C" terminal (low voltage
terminal block) on the integrated control. See
FIGURE 53. A wide variation in the voltage between
Line Neutral and "C" as a function of load indicates
a poor or partial ground. Compare the readings to
TABLE 29. If the readings exceed the maximum
shown, make repairs before before operating the
furnace.
Note - Igntion control in FIGURE 53 is typical. Use
for reference only.
CHECK VOLTAGE BETWEEN LINE NEUTRAL
AND LOW VOLTAGE "C" TERMINAL
W1 W2 G Y2 Y1 C C R DH L O DS
2 - In addition, measure the AC voltage from Line Hot
to Line Neutral (spade terminals) on the integrated
control. See FIGURE 53.This voltage should be in
the range of 97 to 132 Vac.
Furnace Status
Power On Furnace Idle
CAI/Ignitor Energized
Indoor Blower Energized
CHECK VOLTAGE BETWEEN LINE HOT
FIGURE 53
Page 63
TABLE 29
Measurement VAC
Expected
0.3
0.75
Less than 2
AND LINE NEUTRAL
W1 W2 G Y2 Y1 C C R DH L O DS
Maximum
2
5
10