32
TROUBLESHOOTING
If the furnace fails to operate check the following:
• Is the thermostat operating properly?
• Are the blower compartment door(s) in place?
• Is the furnace disconnect closed?
• Has the circuit breaker tripped or the control board
fuse burned open?
• Is the gas turned on?
• Are any manual reset switches open?
• Is the fi lter dirty or plugged?
• Is the fl ame sensor coated? (Remove and clean with
steel wool. Do not use emery cloth or sandpaper!)
• Are all the LED’s on the furnace and motor control
boards constantly ON? If not, refer to Tables 6 - 7 to
determine fault condition.
IMPORTANT NOTE: The furnace will lock out after 5
failed attempts for ignition and will try again every
hour if the call for heat remains.
• If the Inducer Blower is operating, and items above
have been verifi ed, check the Blower Limit Switch
(Figure 41, page 50) and reset if necessary.
• If the furnace operates when the Blower Limit Switch
is reset, contact a qualifi ed service technician to
identify and repair the problem.
• If the furnace still doesn’t operate, check the Flame
Roll-out Switches (Figure 41) and reset if necessary.
• If the furnace operates when the Flame Rollout Switch
is reset, contact a qualifi ed service technician to
identify and repair the problem.
Table 7. Motor Control Board Fault Conditions
Diagnostic
Description
Green
LED
Red
LED
Fixed
Speed
Furnaces
Control Fault (No Power) Off Off
Normal Operation On On
Motor Fault On Flash
Twin Fault (no motor fault) Flash On
Communications Fault Flash Flash
Variable
Speed
Furnaces
Control Fault (No Power) Off Off
Normal Operation On On
Motor Fault On Flash
Communications Fault Flash Flash
Diagnostic Description Green LED Red LED
Control Fault (No Power) Off Off
L1/Neutral Polarity Fault Flash Flash
1 Hour Lockout Alternating Flash
Normal Operation On On
Pressure Switch Closed Fault On Flash
Pressure Switch Open Fault Flash On
Open Limit Switch Fault Flash Off
Motor Fault On Off
Diagnostic Description Yellow LED
Low Flame Sensor Signal Continuous Flash
Flame Present On
Table 6. Furnace Control Board Fault Conditions
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