508151-01
Issue 2104
Page 53 of 72
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 49. 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 26. If the readings
exceed the maximum shown in Table 26, make repairs
before operating the furnace.
2.
In addition, measure the AC voltage from Line Hot
to Line Neutral (spade terminals) on the integrated
control. See Figure 49. This voltage should be in the
range of 97 to 132 VAC
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
Table 26.
CHECK VOLTAGE BETWEEN LINE NEUTRAL
AND LOW VOLTAGE “C” TERMINAL
CHECK VOLTAGE BETWEEN LINE HOT
AND LINE NEUTRAL
W1 W2 G Y2 Y1 C C R DH L O DS
W1 W2 G Y2 Y1 C C R DH L O DS
Figure 49.