TROUBLESHOOTING
75
Symptoms of Abnormal
Opera
�
on
Diagnos
�
c/
Status LED
Codes
Fault Descrip
�
on
Possible Causes
Correc
�
ve Ac
�
on(s)
Notes & Cau
�
ons
• Induced dra
�
blower and
circulator blower runs
con
�
nuously. No furnace
opera
�
on.
• Integrated control module LED
display provides
error code.
• Flame sensed with
no call for heat.
• Short to ground in fame
sense circuit.
• Lingering burner fame.
• Slow closing gas valve.
• Correct short at fame sensor or
in fame sensor wiring.
• Check for lingering fame.
• Verify proper opera
�
on of gas
valve.
• Turn power o
ff
to repair.
• No furnace opera
�
on.
• Integrated control module LED
display provides
error code.
• Flame sensed with
no call for heat.
• Short in low voltage wiring.
• Locate and correct short in low
voltage wiring.
• Turn power OFF prior to
repair.
• Replace fuse with 3-amp
automo
�
ve type.
• Normal furnace opera
�
on with
weak
fla
me signal.
• Integrated control module LED
display provides
error code.
• Flame sense micro
amp signal is low.
• Short in low voltage wiring.
• Clean
fla
me sensor if coated/
oxidized.
• Inspect for proper sensor
alignment.
• Check inlet air piping for
blockage, proper length, elbows,
and termina
�
on.
• Compare current gas pressure to
ra
�
ng plate. Adjust as needed.
• Turn power OFF prior to
repair.
• Clean
fla
me sensor with
steel wool.
• See "Vent/Flue Pipe"
sec
�
on for piping details.
• See ra
�
ng plate for proper
gas pressure.
• Furnace fails to operate.
• Integrated control module LED
display provides
error code.
• Problen with igniter
circuit.
• Improperly connected
igniter.
• Shorted igniter.
• Poor unit ground.
• Igniter relay fault on
integrated control module.
• Check and correct wiring from
integrated control module to
igniter.
• Replace shorted igniter.
• Check and correct unit ground
wiring.
• Check igniter output from control.
Replace if necessary.
• Turn power OFF prior to
repair.
• Replace igniter with
correct replacement part.
• Replace control with
correct replacement part.
• Furnace fails to operate on high
stage; furnace operates normally
on low stage.
• Integrated control module LED
display provides
error code.
• High stage pressure
switch circuit is closed
at start of hea
�
ng
cycle.
• Induced dra
�
blower
is opera
�
ng.
• Furnace is opera
�
ng
on low stage only.
• High stage pressure
switch contacts s
�
cking.
• Shorts in pressure switch
circuit wiring.
.
• Replace high stage pressure
switch.
• Repair short in wiring.
.
• Turn power OFF prior to
repair.
• Replace pressure switch
with proper replacement
part.
• Furnace fails to operate on high
stage; furnace operates normally
on low stage.
• Integrated control module LED
display provides
error code.
• High stage pressure
switch circuit is not
closed.
• Induced dra
�
blower
is opera
�
ng.
• Furnace is opera
�
ng
on low stage only.
• Pressure switch hose
blocked pinched, or
connected improperly.
• Blocked
fl
ue and/or inlet
air pipe, blocked drain
system or weak induced
dra
�
blower.
• Incorrect pressure switch
set point or malfunc
�
oning
switch contacts.
• Loose or improperly connected
wiring.
• Inspect pressure switch hose.
Repair/replace if necessary.
• Inspect
fl
ue and/or inlet air
piping for blockage, proper length,
elbows, and termina
�
on. Check
drain system. Correct as necessary.
• Check induced dra
�
blower
performance. Correct as necessary.
• Correct pressure switch set point or
contact mo
�
on.
• Tighten or correct wiring connec
�
on.
• Turn power OFF prior to
repair.
• Replace pressure switch
with proper replacement
part.
• Replace induced dra
�
blower with proper
replacement part.
• Furnace fails to operate.
• Integrated control module LED
display provide
error code.
• Polarity of 115 volt
AC is reversed.
• Polarity of 115 volt AC power to
furnace or integrated module
is revered.
• Poor unit ground.
• Review wiring diagram to correct
polarity.
• Verify proper ground. Correct if
necessary.
• Check and correct wiring.
• Turn power OFF prior to
repair.
• Furnace fails to operate.
• Integrated control module LED
display provide
error code.
• Gas valve is not
energized when it
should be.
• External Gas Valve
Error.
• Miswired gas valve circuit.
• Open gas valve circuit.
• Gas valve relay on integrated
control board stuck open.
• Check wiring in gas valve circuit.
• Replace integrated control board.
• Turn power OFF prior to
repair.