43
Diagnostic Chart
The dual 7-segment LED display will display an error code that may contain a letter and number. The error code may be used to assist
in troubleshooting the unit.
Symptoms of
Abnormal
Operation
Associated
LED Code
Fault Description Possible Causes
Corrective Actions
Notes and
Cautions
■
Furnace fails to
operate.
■
Integrated
control module
diagnostic LED
display
provides no
signal.
None
■
No 115-volt
power to
furnace, or no
24-volt power to
integrated
control module.
■
Blown fuse or
circuit breaker.
■
Internal fault in
Integrated
control module.
■
Manual disconnect
switch Off, door switch
open or 24-volt wire
improperly connected or
loose.
■
Blown fuse or circuit
breaker.
■
Integrated control
module has an internal
fault.
■
Assure 115-volt power
to the furnace, and
24-volt power to
integrated control
module.
■
Check integrated
control module fuse.
Replace with 3A
automotive fuse, if
necessary.
■
Check for possible
shorts in 115-volt and
24-volt circuits. Repair
as necessary.
■
Replace bad
integrated control
module.
■
Turn off power
prior to repair.
■
Replace
integrated control
module fuse with
3A automotive
fuse.
■
Read precautions
in “Electrostatic
Discharge (ESD)
Precautions”
section of
manual.
■
Replace
integrated control
module with
current
replacement
parts.
■
LED display is
steady on.
Continuous
On
■
Normal
operation.
■
Normal operation.
■
None.
■
Normal operation.
■
Furnace fails to
operate.
■
Integrated
control module
diagnostic LED
is flashing
1 flash.
1 flash
■
Furnace lockout
due to an
excessive
number of
ignition “retries”
(3 total).
■
Failure to establish
flame. No gas to
burners, front cover
pressure switch stuck
open, bad igniter or
igniter alignment,
improper orifices or
coated/oxidized or
improperly connected
flame sensor.
■
Loss of flame after
establishment.
Interrupted gas supply,
lazy burner flames
(improper gas pressure
or restriction in flue and/
or combustion air
piping), front cover
pressure switch
opening, or improper
induced draft blower
performance.
■
Locate and correct gas
interruption.
■
Check front cover
pressure switch
operation (hose,
wiring, contact
operation). Correct if
necessary.
■
Replace or realign
igniter. Igniter is fragile,
handle gently.
■
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.
■
Turn off power
prior to repair.
■
Igniter is fragile,
handle with care.
■
Sand flame
sensor with
emery cloth.
■
See “Vent/Flue
Pipe” section for
piping details.
Goodman 118 Long
HIGH VOLTAGE!
WARNING
To avoid personal injury or death due to electrical shock, disconnect electrical power
before performing any service or maintenance.
