Page 44
I- Proper Ground and Voltage
WARNING
Electric Shock Hazard. Can cause injury
or death. Unit must be properly grounded
in accordance with national and local
codes.
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 54. 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 readings exceed the maximum shown in TABLE
21, 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 54. This voltage should be in
the range of 97 to 132 Vac.
Note -
Figure 55 is a typical ignition control illustration.
TABLE 21
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 54
