SYSTEM OPERATION
87
T
ROUBLESHOOTING
C
HART
4
4 FLASHES
• Circulator blower runs
continuously. No furnace
operation.
• Integrated control module
diagnostic
LED
is flashing
FOUR
(4) flashes.
6
6 FLASHES
7
7 FLASHES
• Furnace fails to operate.
• Integrated control module
diagnostic
LED
is flashing
SIX
(6) flashes.
• Normal furnace
operation.
• Integrated control
module diagnostic
LED
is flashing
SEVEN
(7)
flashes.
• Rollout limit
open.
• Flame sense
microamp signal is
low.
• Insufficient conditioned
air over the heat
exchanger. Blocked
filters, restrictive
ductwork, improper
circulator blower speed,
or failed circulator
blower.
• Check filters and
ductwork for blockage.
Clean filters or remove
obstruction.
• Check circulator blower
speed and perfor-
mance. Correct speed
or replace blower if
necessary.
• Turn power OFF
prior to repair.
• See Product
Data Bulletin for
allowable rise
range and
proper circulator
speed.
• Flame sensor is coated/
oxidized.
• Flame sensor incor-
rectly positioned in
burner flame.
• Lazy burner flame due
to improper gas
pressure or combustion
air.
• 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.
• Turn power OFF
prior to repair.
• Clean flame
sensor with
steel wool.
• See “Vent/Flue
Pipe” section for
piping details.
• See rating plate
for proper gas
pressure.
• See “Vent/Flue
Pipe” section for
piping details.
• Replace induced
draft blower
with proper
replacement
part.
• Primary limit
circuit is
open.
• Integrated control module
diagnostic
LED
is flashing
continuously.
C
CONTINUOUS
FLASHING
• Polarity of 115 volt
or 24 volt power
is reversed.
• 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.
• Review wiring diagram
to correct polarity.
• Reverse wires
connected to 24 volt
side of transformer.
• Verify proper ground.
Correct if necessary.
• Check and correct
wiring if necessary.
• Turn power OFF
prior to repair.
8
8 FLASHES
3
• Check and correct
wiring from inte-
grated control module
to igniter.
• Replace Bad igniter.
• Check and correct
unit ground wiring.
• Furnace not operating.
• Integrated control
module diagnostic
LED
is flashing
EIGHT
(8)
flashes.
• Problem with
igniter ciruit.
• Improperly connected
igniter.
• Bad igniter.
• Poor unit ground.
• Turn power OFF
prior to repair.
• Replace igniter
with proper
replacement
part.
• Normal operation.
• LED is steady on
On Steady
• Flame rollout.
• Misaligned burners,
blocked flue and/or air
inlet pipe, or failed
induced draft blower.
• Loose or improperly
connected wiring.
• 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.
• Induced draft blower
and circulator blower
runs continuously. No
furnace operation.
• Integrated control
module diagnostic
LED
is
flashing
FIVE
(5) flashes.
5
5 FLASHES
• Flame sensed
with no call
for heat.
• Short to ground in flame
sense circuit.
• Lingering burner flame.
• Slow closing gas valve.
• Correct short at flame
sensor or in flame
sensor wiring.
• Check for lingering
flame.
• Verify proper operation
of gas valve.
• Turn power
OFF prior to
repair.
Fault
Description(s)
Symptoms of Abnormal
Operation
Associated
Possible Causes
Corrective Action
Cautions and Notes
• Normal operation.
• None.
• Normal operation.
AMH8, AMS8, ADS8, DDS8, DMS8, DHS8,
GME8, GMH8, GMS8, GDH8, GDS8, GHS8
LED
Code
(2)(5)
2
LED Flash codes will cease if power to the control module is interrupted through the disconnect or door switch.
3
8 Flases - applies to AMS8/ADS8 Models only (Silicon Nitride Models Only)
5
Integrated circuit boards on new furnace models AMH, GMH, GCH, GMS, GDS, GHS, GKS hold last 5 faults for service reference.