Appendix; Troubleshooting Chart - Goodman MH8 Installation Instructions Manual

T
ROUBLESHOOTING
Associated
Symptoms of
Abnormal Operation
• 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.
Integrated control module will automatically attempt to reset from lockout after one hour.
1
2 LED Flash code will cease if power to the control module is interrupted through the disconnect or door switch.
C
HART
Fault
LED Code Description(s)
2
NONE • No 115 volt power 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
attempts. (3 total)
1 FLASH
• Auxiliary Limit Open
• Pressure switch
circuit is closed.
2
• Induced draft blower
is not operating.
2 FLASHES
• Pressure switch
circuit not closed.
3
• Induced draft blower
is operating.
3 FLASHES
• If installed, manual
reset limit switch is
open on Masonry
Vent Kit (MVK).
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
1 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.
• Blockage in flue or
chimney.
37
Corrective
Action
• Assure 115 and 24 volt
power to furnace
integrated control
module.
• Check integrated control
module fuse (3A).
Replace if necessary.
• Check for possible
• Turn power OFF
shorts in 115 and 24 volt
circuits. Repair as
necessary.
• Read precautions
• 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.
• Turn power OFF
• Replace induced
draft blower
pressure switch.
• Replace pressure
• Repair short.
• Inspect pressure switch
• Turn power OFF
hose. Repair, if neces-
sary,
• See "Combustion
• Inspect flue for blockage,
proper length, elbows,
and termination.
• Correct pressure switch
setpoint or contact
• Replace pressure
motion.
• Tighten or correct wiring
connection.
• Replace masonry
• Inspect masonry
chimney and flue; remove
blockage.
Cautions
& Notes
• Turn power OFF
prior to repair.
• Replace integrated
control module
fuse with 3A
automotive fuse.
prior to repair.
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.
prior to repair.
switch with proper
replacement part.
prior to repair.
and Ventilation Air
Requirements" and
"Category I Venting
(Vertical Venting)"
section for details.
switch with proper
replacement part.
vent kit limit switch
with correct
replacement part.