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I− Proper Ground and Voltage
A poorly grounded furnace can contribute to premature ig-
nitor 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 50. 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 the table below. If the read-
ings exceed the maximum shown in table 1, make re-
pairs before operating the furnace.
2 − In addition, measure the AC voltage from Line Hot to
Line Neutral (spade terminals) on the integrated con-
trol. See figure 50. This voltage should be in the range
of 97 to 132 Vac
TABLE 17
Furnace Status
Measurement VAC
Expected
Maximum
Power On Furnace Idle
0.3
2
CAI / Ignitor Energized
0.75
5
Indoor Blower Energized
Less than 2
10
CHECK VOLTAGE BETWEEN LINE NEUTRAL
AND LOW VOLTAGE C" TERMINAL
Red LED
Recall
Red LED
Recall
CHECK VOLTAGE BETWEEN LINE HOT
AND LINE NEUTRAL
FIGURE 50