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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 filter dirty or plugged?
* Is the flame 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 verified, 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 qualified 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 qualified service technician
to
identify and repair the problem.
i
O agnost c
Description
Control Fault (No Power)
L1/Neutral Polarity Fault
1 Hour Lockout
Normal Operation
Pressure Switch Closed Fault
Pressure Switch Open Fault
Open Limit Switch Fault
Motor Fault
Green LED
Red
LED
Off
Off
Flash
Flash
Alternating
Flash
On
On
On
Flash
Flash
On
Flash
Off
On
Off
Diagnostic
Description
I
Yellow LED
Low Flame Sensor Signal
Continuous
Flash
Flame Present
On
Table 6. Furnace Control Board Fault Conditions
FJ×ed
Speed
Furnaces
Variable
speea
Furnaces
Table 7.
Diagnostic
Green
Description
LED
Control Fault (No Power)
Normal Operation
Motor Fault
Twin Fault (no motor fault)
Communications
Fault
Control Fault (No Power)
Normal Operation
Motor Fault
Communications
Fault
Off
On
On
Flash
Flash
Off
On
On
Flash
Red
LED
Off
On
Flash
On
Flash
Off
On
Flash
Flash
Motor Control Board Fault Conditions
32
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