GMES8 GCES8 Service Manual

TROUBLESHOOTING
37
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.
• Circulator blower runs
continuously. No furnace
operation.
• Integrated control
module diagnostic LED
is ashing FOUR (4)
ashes.
• Primary limit circuit
is open.
• Check primary limit.
Replace if necessary.
• Check lters and
ductwork for blockage.
Clean lters or remove
obstruction.
• Check circulator blower
speed and performance.
Correct speed or replace
blower if necessary.
• Tighten or correct wiring
connection.
• Turn power OFF
prior to repair.
• Replace primary
limit with proper
replacement part.
• Replace blow-
er with correct
replacement part.
4
4 FLASHES
• Faulty primary limit switch.
• Insufcient conditioned air
over the heat exchanger.
Blocked lters, restrictive
ductwork, improper circula-
tor blower speed, or failed
circulator blower.
• Loose or improperly con-
nected wiring.
Fault Description(s)
Possible Causes
Corrective Action
Cautions and
Notes
Symptoms of Abnormal
Operation
Associated
LED Code
2
• Normal furnace opera-
tion.
• Integrated control
module diagnostic LED
is ashing SEVEN (7)
ashes.
• Flame sense micro-
amp signal is low.
• Clean ame sensor if
coated/oxidized.
• Inspect for proper sensor
alignment.
• Check inlet air piping for
blockage, proper length,
elbows, and termination.
• Compare current gas
pressure to rating plate
info. Adjust as needed.
• Turn power OFF
prior to repair.
• Clean ame sen-
sor
• See “Vent/Flue
Pipe” section for
piping details.
• See rating plate
for proper gas
pressure.
7
7 FLASHES
• Flame sensor is coated/
oxidized.
• Flame sensor incorrectly
positioned in burner ame.
• Lazy burner ame due to
improper gas pressure or
combustion air.
• Induced draft blower and
circulation blower runs
continuously. No furnace
operation.
• Integrated control
module diagnostic LED
is ashing FIVE (5)
ashes.
• Flame sensed with
no call for heat.
• Correct short at ame
sensor or in ame
sensor wiring.
• Turn power OFF
prior to repair.
5
5 FLASHES
• Short to ground in ame
sense circuit.
• Circulator blower runs
continuously. No furnace
operation.
• Integrated control mod-
ule diagnostic LED is
ashing SIX (6) ashes.
• Rollout limit circuit is
open.
• Check burners for proper
alignment.
• Check ue and air inlet
piping for blockage, prop-
er length, elbows, and
termination. Correct as
necessary.
• Check rollout limit. Re-
place if necessary.
• Check induced draft blow-
er for proper performance.
Replace, if necessary.
• Tighten or correct wiring
connection.
• Turn power OFF
prior to repair.
• See “Vent/Flue
Pipe” section for
piping details.
• Replace rollout
limit with correct
replacement part.
• Replace induced
draft blower with
correct replace-
ment part.
6
6 FLASHES
• Flame rollout.
• Misaligned burners, blocked
ue and/or air inlet pipe, or
failed induced draft blower.
• Loose or improperly con-
nected wiring.
• Faulty rollout limit.
• Furnace fails to operate.
• Integrated control mod-
ule diagnostic LED is
ashing continuously.
• Polarity of 115 or
24 volt power is
reversed.
• Review wiring diagram
to correct polarity.
• Reverse orange and
gray wires going to
transformer.
• Verify proper ground.
Correct if necessary.
• Turn power OFF
prior to repair.
C
CONTINUOUS/
RAPID FLASH
• Polarity of 115 volt AC pow-
er to furnace or integrated
control module is reversed.
• Orange and gray wires to
transformer are reversed.
• Poor unit ground.
PCBBF145(S) CONTROL BOARD