SYSTEM OPERATION
89
2
LED flash code will cease if power to control module is interrupted throught the disconnect or door switch.
3
8 Flashes - Applies to AMS95, AMS9, ACS9 Models only (Silicon Nitride Models Only)
TROUBLESHOOTING CHART
AMS9, ACS9, DMS9, DCS9, GMS9,
GCS9, GKS9, AMS95, GMS95
5
5 FLASHES
6
6 FLASHES
8
8 FLASHES
• Turn power OFF
prior to repair.
• Replace primary/
auxiliary limit
switch with
proper replace-
ment part.
• Replace blower
with correct
replacement part.
• Turn power OFF
prior to repair.
• Sand flame sensor
with emery clot.
• See “Vent/Flue
Pipe” section for
piping details.
• See rating plate for
proper gas
pressure.
• Circulator blower runs
continuously. No
furnace operation.
• Integrated control
module diagnostic LED
is flashing FOUR (4)
flashes.
• Primary or
auxiliary limit
circuit is open.
• Check primary/auxiliary limit.
Replace if necessary
• Check filters and ductwork
for blockage. Clean filters or
remove obstruction.
• Check circulator blower
speed and performance.
Correct speed or replace
blower if necessary.
• Tighten or correct wiring
connection.
4
4 FLASHES
• Insufficient conditioned air
over the heat exchanger.
Blocked filters, restrictive
ductwork, improper
circulator blower speed, or
failed circulator blower.
• Faulty primary or auxiliary
limit switch.
• Loose or improperly
connected wiring.
Fault
Description(s)
Possible Causes Corrective Action Cautions and Notes
Symptoms of Abnormal
Operation
Associated
LED Code
2
• Furnace not operating.
• Integrated control
module diagnostic LED
is flashing EIGHT (8)
flashes.
• Problem with
igniter circuit.
• Check and correct wiring
from integrated control
module to igniter.
• Replace bad igniter.
• Check and correct unit
ground wiring.
• Turn power OFF
prior to repair.
• Replace igniter
with proper
replacement part.
• Improperly connected
igniter.
• Bad igniter.
• Poor unit ground.
• Normal furnace
operation.
• Integrated control
module diagnostic LED
is flashing SEVEN (7)
flashes.
• Flame sense
microamp signal
is low.
• Sand flame sensor is
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.
7
7 FLASHES
• Flame sensor is coated/
oxidized.
• Flame sensor incorrectly
positioned in burner flame.
• Lazy burner flame 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 flashing FIVE (5)
flashes.
• Flame sensed
with no call
for heat.
• Correct short at flame
sensor or in flame
sensor wiring.
• Turn power OFF
prior to repair.
• Short to ground in flame
sense circuit.
• Circulator blower runs
continuously. No
furnace operation.
• Integrated control
module diagnostic LED
is flashing SIX (6)
flashes.
• Rollout limit
circuit is open.
• Check burners for
proper alignment.
• Check flue and air inlet
piping for blockage,
proper length, elbows,
and termination. Correct
as necessary.
• Check induced draft
blower 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.
• Flame rollout.
• Misaligned burners,
blocked flue and/or air
inlet pipe, or failed
induced draft blower.
• Loose or improperly
connected wiring.
• Faulty rollout limit.
• Furnace fails to
operate.
• Integrated control
module diagnostic LED
is flashing continu-
ously.
• Polarity of 115
or 24 volt
power is
reversed.
• Review wiring diagram to
correct polarity.
• Reverse wires going to
24 volt side of trans-
former.
• Verify proper ground.
Correct if necessary.
• Turn power OFF
prior to repair.
C
CONTINUOUS/
RAPID FLASH
• Polarity of 115 volt AC
power to furnace or
integrated control module is
reversed.
• Wires to 24 volt side of
transformer are reversed.
• Poor unit ground.
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