TROUBLESHOOTING
48
Symptoms of Abnormal
Operation
Associated
LED Code
2
Fault Description(s)
Possible Causes
Corrective Action
Cautions and Notes
• Furnace fails to operate.
• Integrated control module
diagnostic
LED
provides
no
signal
.
OFF
• No 115 volt power
to furnace, or no
24 volt power to
integrated control
module.
• Blown fuse or circuit
breaker.
•Integrated control
module has an
internal fault.
• Manual disconnect
switch OFF, door
switch open, or
24 volt wires improperly
connected or loose.
• Blown fuse or circuit
breaker.
• Integrated control
module has an
internal fault.
• Assure 115 and 24 volt
power to furnace
integrated control
module.
• Check integrated
control module fuse
(3A). Replace if
necessary.
• Check for possible
shorts in 115 and 24
volt circuits. Repair as
necessary.
• Replace bad integrated
control module.
• Turn power OFF
prior to repair.
• Replace integrated
control module fuse
with 3A automotive
fuse.
• Read precautions in
“Electrostatic
Discharge" section of
manual.
• LED is Steady On.
CONTINUOUS
ON
• Normal Operation
• Normal Operation
• None
• Normal Operation
• Furnace fails to operate.
• Integrated control
module diagnostic
LED
is
flashing
ONE
(1) flash.
1 FLASH
• Furnace lockout due to
an excessive number of
ignition "retries"
(3 total)
1
.
• Failure to establish
flame. Cause may be no
gas to burners, front
cover pressure switch
stuck open, bad igniter
or igniter alignment,
improper orifices,
coated/oxidized or
improperly connected
flame sensor.
• Loss of flame after
establishment. Cause
may be interrupted gas
supply, lazy burner
flames (improper gas
pressure or restriction
in flue and/or
combustion air piping),
front cover pressure
switch opening, improper
induced draft blower
performance.
• Locate and correct
gas interruption.
• Check front cover
pressure switch
operation (hose, wiring,
contact operation).
Correct if necessary.
• Replace or realign
igniter.
• Check flame sense
signal. Sand sensor if
coated and/or oxidized.
• Check flue piping for
blockage, proper
length, elbows, and
termination.
• Verify proper induced
draft blower
performance.
• Turn power OFF prior
to repair.
• Igniter is fragile,
handle with care.
• Sand flame sensor with
emery cloth.
• See "Vent/ Flue Pipe"
section for piping
details.
• Furnace fails to operate.
• Integrated control
module diagnostic
LED
is
flashing
TWO
(2) flashes.
2 FLASHES
• Pressure switch circuit
is closed.
• Induced draft blower
is
not
operating.
• Induced draft blower
pressure switch
contacts sticking.
• Shorts in pressure
switch circuit.
• Replace induced draft
blower pressure switch.
• Repair short.
• Turn power OFF prior
to repair.
• Replace pressure
switch with proper
replacement part.
• Induced draft blower runs
continuously with no further
furnace operation.
• Integrated control
module diagnostic
LED
is
flashing
THREE
(3) flashes.
3 FLASHES
• Pressure switch circuit
not closed.
• Induced draft blower
is
operating.
• Pressure switch hose
blocked, pinched or
connected improperly.
• Blocked flue and/or
inlet air pipe, blocked
drain system, or weak
induced draft blower.
• Incorrect pressure
switch setpoint or
malfunctioning switch
contacts.
• Loose or improperly
connected wiring.
• Inspect pressure switch
hose. Repair, if
necessary.
•Inspect flue and/or inlet
air piping for blockage,
proper length, elbows,
and termination. Check
drain system. Correct as
necessary.
• Correct pressure switch
setpoint or contact
motion.
• Tighten or correct
wiring connection.
• Turn power OFF prior
to repair.
• Replace pressure
switch with proper
replacement part.
ON
1
2
3