Troubleshooting Chart - Goodman GMH8 Installation Instructions Manual

TROUBLESHOOTING CHART
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)
flash.
Furnace fails to operate.
Integrated control
module diagnostic LED
is flashing TWO (2)
flashes.
• Induced draft blower
runs continuously with
no further furnace
operation.
• Integrated control
module diagnostic LED
is flashing THREE (3)
flashes.
NONE
• No 115 volt power
to furnace, or no 24
volt power to
integrated control
module.
• Manual disconnect switch
OFF, door switch open, or
24 volt wires improperly
connected or loose.
1 FLASH
2 FLASHES
3 FLASHE_
• Blown fuse or
circuit breaker.
• Integrated control
module has an
internal fault.
• Furnace lockout due
to an excessive
number of ignition
attempts. (3 total) _
• Auxiliary Limit Open
• Pressure switch
circuit is closed.
• Induced draft
blower is not
operating.
• Pressure switch
circuit not closed.
• Induced draft
blower is operating.
• Blown fuse or circuit
breaker.
• Integrated controi 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.
• 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.
• 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
performance.
• Check circulator
blower speed and
performance.
Correct speed or
replace blower if
necessary.
• Replace induced
draft blower
pressure switch.
• Repair short.
• 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.
• Turn power OFF
prior to repair.
Replace integrated
control module
fuse with 3A
automotive fuse.
• Turn power OFF
prior to repair.
• Read precautions
in "Electrostatic
Discharge" section
of manual.
• 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
replacement part.
• 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
replacement part.
1Integrated 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.
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