• Induced draft blow er
runs continuously w ith no
further furnace operation.
• Integrated control module LED
display provides
error code.
• Low stage
pressure sw itch
circuit is not closed.
• Pressure sw itch hose
blocked pinched, or
connected improperly.
• Blocked fue and/or inlet air
pipe, blocked drain system
or w eak induced draft
blow er.
• Incorrect pressure sw itch
set point or malfunctioning
sw itch contacts.
• Loose or improperly
connected w iring.
• Circulator blow er runs
continuously. No furnace
operation.
• Integrated control module LED
display provides
error code.
• Primary limit circuit
is open.
• Insuffcient conditioned air
over the heat exchanger.
Blocked flters, restrictive
ductw ork, improper
circulator blow er speed, or
failed circulator blow er
motor.
• Loose or improperly
connected w iring in high limit
circuit.
• Inspect pressure sw itch hose.
Repair/replace if necessary.
• Inspect fue and/or inlet air piping
for blockage, proper length,
elbow s, and termination. Check
drain system. Correct as
necessary.
• Check induced draft blow er
performance. Correct as
necessary.
• Correct pressure sw itch set
point or contact motion.
• Tighten or correct w iring
connection.
• Turn pow er OFF prior to
repair.
• Replace pressure sw itch
w ith proper replacement part.
• Replace induced draft
blow er w ith proper
replacement part.
• Check flters and ductw ork for
blockage. Clean flters or remove
obstruction.
• Check circulator blow er speed
and performance. Correct
speed or replace blow er motor if
necessary.
• Tighten or correct w iring
connection.
• Turn pow er OFF prior to
repair.
• See Specifcation Sheet
applicable to your model* for
allow able rise range and
proper circulator speed.
• Furnace fails to operate
• Integrated control module LED
display provides no signal.
None
• No 115 pow er to
furnace or no 24 volt
pow er to integrated
control module
• Blow n fuse or
tripped circuit breaker
• Integrated control
module is non-
functional
• Check 115 pow er to furnace and
integrated control module.
• Check for possible shorts in 115
circuit. Repair as necessary.
• Replace non-functional
integrated control module.
• Turn pow er OFF prior to
repair.
• Read precautions in
“Electrostatic
Discharge” section of manual.
• Replace control w ith
correct replacement part
• LED display indicates
n
o
it
a
r
e
p
o
l
a
m
r
o
N
•
n
o
it
a
r
e
p
o
l
a
m
r
o
N
•
• Furnace fails to operate
• Integrated control module LED
display provides
error code.
• Furnace lockout due
to an excessive
number of ignition
“retries” (3 total)
• Turn pow er OFF prior to
repair.
• Igniter is fragile, handle w ith
care.
• Clean fame sensor w ith
steel w ool.
• See “Vent/Flue Pipe”
section for piping details.
• Furnace fails to operate.
• Integrated control module LED
display provides
error code.
.
• Low stage
pressure sw itch
circuit is closed at
start of heating cycle.
• Turn pow er OFF prior to
repair.
• Replace pressure sw itch
w ith proper replacement part.
• Normal operation
• None
• Failure to establish flame.
Cause may be no gas to
burners, front cover
pressure sw itch stuck
open, bad igniter or igniter
alignment, improper orifces,
or coated/oxidized or
improperly connected fame
sensor.
• Loss of fame after
establishment. Cause may
be interrupted gas supply,
lazy burner fames (improper
gas pressure or restriction
in fue and/ or combustion air
piping),
front cover pressure sw itch
opening, or improper
induced draft blow er
performance.
• Locate and correct gas
interruption.
• Check front cover pressure
sw itch operation (hose, w iring,
contact operation). Correct if
necessary.
• Replace or realign igniter.
• Check fame sense signal. Sand
sensor if coated and/or oxidized.
• Check fue piping for blockage,
proper length, elbow s, and
termination.
• Verify proper induced draft
blow er performance.
• Low stage pressure
sw itch contacts sticking.
• Shorts in pressure sw itch
circuit w iring.
• Replace low stage pressure
sw itch.
• Repair short in w iring.
Symptoms of Abnormal
Operation
Diagnostic /
Status LED
Codes
Possible Causes
Corrective Actions
Notes & Cautions
• Manual disconnect sw itch
turned OFF, door sw itch
open or 24 volt w ire
improperly connected or
loose
• Furnace electrical supply
shared w ith other devices
• Integrated control module
is non-functional
Fault Description
TROUBLESHOOTING
47
