SYSTEM OPERATION
86
TROUBLESHOOTING CHART
1
Integrated control module will automatically attempt to reset from lockout after one hour.
2
LED Flash code will cease if power to the control module is interrupted through the disconnect or door switch.
• Turn power OFF
prior to repair.
• Igniter is fragile,
handle with care.
• Clean flame
sensor with steel
wool.
• See “Combustion
and Ventilation Air
Requirements”
and “Category I
Venting (Vertical
Venting)” section
for details.
• See Product Data
Bulletin for
allowable rise
range and proper
circulator speed.
• Turn power OFF
prior to repair.
• Replace pressure
switch with
proper replace-
ment part.
• Read precautions
in “Electrostatic
Discharge”
section of manual.
• Turn power OFF
prior to repair.
• Replace integrated
control module
fuse with 3A
automotive fuse.
Cautions and Notes
• Furnace lockout due
to an excessive
number of ignition
attempt (1 total) and
“retries” (2 total)
1
.
After a total of 3
tries for ignition,
lockout occurs.
"Recycles" are
infinite.
• Auxiliary Limit Open
• Locate and correct
gas interruption.
• 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 perfor-
mance.
• Check circulator
blower speed and
performance. Correct
speed or replace
blower if necessary.
• Furnace fails to operate.
• Integrated control
module diagnostic LED
is flashing ONE (1)
flash.
1
1 FLASH
• Failure to establish flame.
Cause may be no gas to
burners, bad igniter or
igniter alignment, improper
orifices, or 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 or
improper induced draft
blower performance.
• Insufficient conditioned air
over the heat exchanger.
Blocked filters, restrictive
ductwork, improper
circulator blower speed,
or failed circulator
blower.
• Pressure switch
circuit is closed.
• Induced draft
blower is not
operating.
• Replace induced draft
blower pressure
switch.
• Repair short.
• Furnace fails to
operate.
• Integrated control
module diagnostic LED
is flashing TWO (2)
flashes.
2
• Induced draft blower
pressure switch contacts
sticking.
• Shorts in pressure switch
circuit.
• Inspect pressure
switch hose. Repair,
if necessary,
• Inspect flue for
blockage, proper
length, elbows, and
termination.
• Correct pressure
switch setpoint or
contact motion.
• Tighten or correct
wiring connection.
• Pressure switch hose
blocked, pinched or
connected improperly.
• Blocked flue or weak
induced draft blower.
• Incorrect pressure switch
setpoint or malfunctioning
switch contacts.
• Loose or improperly
connected wiring.
• Pressure switch
circuit not closed.
• Induced draft
blower is operating.
• Induced draft blower
runs continuously with
no further furnace
operation.
• Integrated control
module diagnostic LED
is flashing THREE (3)
flashes.
3
3 FLASHES
• Turn power OFF
prior to repair.
• See “Combustion
and Ventilation Air
Requirements”
and “Category I
Venting (Vertical
Venting)” section
for details.
• Replace pressure
switch. with
proper replace-
ment part.
• Integrated control
module has an
internal fault.
• Integrated control module
has an internal fault.
• Replace bad integrated
control module.
• Furnace fails to
operate.
• No 115 volt power
to furnace, or no 24
volt power to
integrated control
module.
• Blown fuse or
circuit breaker.
• Manual disconnect switch
OFF, door switch open, or
24 volt wires improperly
connected or loose.
• Blown fuse or circuit
breaker.
• 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.
• Furnace fails to
operate.
• Integrated control
module diagnostic LED
provides no signal.
NONE
Fault Description(s) Possible Causes Corrective Action
Symptoms of Abnormal
Operation
Associated
LED Code
2
2 FLASHES
AMH8, AMS8, ADS8, DDS8, DMS8, DHS8,
GME8, GMH8, GMS8, GDS8, GHS8
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