Goodman GMS8 Installation & Operating Instructions Manual page 29

Associated
Symptoms of Abnormal
Operation
LED Code
• Furnace fails to operate.
• Integrated control
module diagnostic LED
provides no signal.
• Furnace fails to operate.
• Furnace fails to operate.
• Integrated control
module diagnostic LED
is flashing ONE (1)
1 FLASH
flash.
• Furnace fails to operate.
• Integrated control
module diagnostic LED
is flashing TWO (2)
2 FLASHES
flashes.
• Induced draft blower
runs continuously with
no further furnace
operation.
3 FLASHES
• Integrated control
module diagnostic LED
is flashing THREE (3)
flashes.
Integrated control module will automatically attempt to reset from lockout after one hour.
1
LED Flash code will cease if power to the control module is interrupted through the disconnect or door switch.
2
TROUBLESHOOTING CHART
Fault Description(s)
2
• No 115 volt power
NONE
to furnace, or no 24
volt power to
integrated control
module.
• Blown fuse or
circuit breaker.
• Integrated control
module has an
internal fault.
• Furnace lockout due
to an excessive
1
number of ignition
attempt (1 total) and
"retries" (3 total) .
1
• Auxiliary Limit Open
• Pressure switch
circuit is closed.
2
• Induced draft
blower is not
operating.
• Pressure switch
circuit not closed.
3
• Induced draft
blower is operating.
Possible Causes
• 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.
• 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.
• Induced draft blower
pressure switch contacts
sticking.
• Shorts in pressure switch
circuit.
• 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.
29
Corrective Action Cautions and Notes
• Assure 115 and 24 volt
• Turn power OFF
power to furnace
integrated control
module.
• Check integrated control
module fuse (3A).
• Replace integrated
Replace if necessary.
• Check for possible
shorts in 115 and 24 volt
circuits. Repair as
necessary.
• Turn power OFF
• Replace bad integrated
control module.
• Read precautions
• Turn power OFF
• Locate and correct
gas interruption.
• Igniter is fragile,
• Replace or realign
igniter.
• Clean flame
• Check flame sense
signal. Sand sensor if
coated and/or
oxidized.
• See "Combustion
• Check flue piping for
blockage, proper
length, elbows, and
termination.
• Verify proper induced
draft blower
• See Product Data
performance.
• Check circulator
blower speed and
performance. Correct
speed or replace
blower if necessary.
• Replace induced draft • Turn power OFF
blower pressure
switch.
• Replace pressure
• Repair short.
• Turn power OFF
• Inspect pressure
switch hose. Repair, if
necessary,
• See "Combustion
• Inspect flue for
blockage, proper
length, elbows, and
termination.
• Correct pressure
switch setpoint or
contact motion.
• Replace
• Tighten or correct
wiring connection.
prior to repair.
control module
fuse with 3A
automotive fuse.
prior to repair.
in "Electrostatic
Discharge" section
of manual.
prior to repair.
handle with care.
sensor with steel
wool.
and Ventilation Air
Requirements" and
"Category I
Venting (Vertical
Venting)" section
for details.
Bulletin for
allowable rise
range and proper
circulator speed.
prior to repair.
switch with
proper
replacement part.
prior to repair.
and Ventilation
Air
Requirements"
and "Category I
Venting (Vertical
Venting)" section
for details.
pressure switch
with proper
replacement part.