TROUBLESHOOTING
39
Symptoms of Abnormal Operation
Associated
LED Code
2
Fault Description(s)
Possible Causes
Corrective Action
Cautions and Notes
• 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.
• Circulator blower runs continuously.
No furnace operation.
• Integrated control
module diagnostic
LED
is
flashing
FOUR
(4) flashes.
4 FLASHES
• Primary or auxiliary
limit circuit is open.
• Faulty primary or
auxiliary limit switch.
• Insufficient conditioned
air over the heat
exchanger. Blocked filters,
restrictive ductwork,
improper circulator blower
speed, or failed circulator
blower.
• Loose or improperly
connected wiring.
• Check primary/
auxiliary limit.
Replace if necessary.
• Check filters and
ductwork for blockage.
Clean filters or remove
obstruction.
• Check circulator blower
speed and performance.
Correct speed or replace
blower if necessary.
• Tighten or correct
wiring connection.
• Turn power OFF prior
to repair.
• Replace primary/
auxiliary limit with
proper replacement
part.
• Replace blower with
correct replacement
part.
• Induced draft blower and
circulation blower runs
continuously. No furnace
operation.
• Integrated control module
diagnostic
LED
is flashing
FIVE
(5) flashes.
5 FLASHES
• Flame sensed with no
call for heat.
• Short to ground in
flame sense circuit.
• Correct short at flame
sensor or in flame sensor
wiring.
• Turn power OFF prior
to repair.
• Furnace fails to operate.
• Integrated control module
diagnostic
LED
is flashing
SIX
(6) flashes.
• No furnace operation.
6 FLASHES
•Rollout limit open.
•Integrated control module
fuse is blown.
• Flame rollout.
• Misaligned burners,
blocked flue and/or air
inlet pipe, or failed
induced draft blower.
• Loose or improperly
connected wiring.
• Short in 24 volt AC
control circuits or safety
circuits.
• Faulty rollout limit.
• Check burners for
proper alignment.
• Check flue and air inlet
piping for blockage,
proper length, elbows,
and termination.
Correct as necessary.
• Check rollout limit.
Replace if necessary.
• Check induced draft
blower for proper
performance. Replace,
if necessary.
• Tighten or correct
wiring connection.
• Turn power OFF prior
to repair.
• See "Vent/Flue Pipe"
section for piping
details.
• Replace induced draft
blower with correct
replacement part.
• Replace integrated
control module fuse
with 3A automotive
fuse.
• Read precautions in
“Electrostatic
Discharge" section
of manual.
• Replace rollout limit
with correct
replacement part.
• Normal furnace operation.
• Integrated control module
diagnostic
LED
is flashing
SEVEN
(7) flashes.
7 FLASHES
• Flame sense microamp
signal is low.
• Flame sensor is
coated/oxidized.
• Flame sensor
incorrectly positioned
in burner flame.
• Lazy burner flame
due to improper gas
pressure or
combustion air.
• Sand flame sensor.
• Inspect for proper
sensor alignment.
• Compare current gas
pressure to rating plate
info. Adjust as needed.
• Turn power OFF prior
to repair.
• Clean flame sensor
with steel wool.
• See "Vent/Flue Pipe"
section for
piping details.
• See rating plate for
proper gas pressure.
3
4
5
6
7