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Symptoms of
Diagnostic/
Abnormal
Status LED
Operation
Code
Furnace fails to
E1
operate.
Integrated
control module
LED display
provides "E1"
error code.
Induced draft
E2
blower runs
continuously
with no further
furnace
operation.
Integrated
control module
LED display
provides "E2"
error code.
Circulator
E3
blower runs
continuously.
No furnace
operation.
Integrated
control module
LED display
provides "E3"
error code.
Induced draft
E4
blower and
circulator
blower runs
continuously.
No furnace
operation.
Integrated
control module
LED display
provides "E4"
error code.
Fault Description Possible Causes
Low-stage
Low-stage
pressure switch
pressure switch
circuit is closed
contacts sticking.
at start of
Shorts in pressure
heating cycle.
switch circuit
wiring.
Low-stage
Pressure switch
pressure switch
hose blocked,
circuit is not
pinched or
closed.
connected
improperly.
Blocked flue and/or
inlet air pipe,
blocked drain
system or weak
induced draft
blower.
Incorrect pressure
switch setpoint or
malfunctioning
switch contacts.
Loose or
improperly
connected wiring.
Primary limit or
Insufficient
auxiliary limit
conditioned air
circuit is open.
over the heat
exchanger.
Rollout limit
Blocked filters,
circuit is open.
restrictive
ductwork, improper
circulator blower
speed, or failed
circulator blower.
Flame rollout.
Misaligned
burners, blocked
flue and/or air inlet
pipe or failed
induced draft
blower.
Loose or
improperly
connected wiring.
Flame sensed
Short to ground in
with no call for
flame sense circuit.
heat.
Lingering burner
flame.
Slow closing gas
control valve.
Corrective Actions
Replace low-stage
pressure switch.
Repair short in wiring.
Inspect pressure
switch hose. Repair/
replace, if necessary,
Inspect flue and/or
inlet air piping for
blockage, proper
length, elbows and
termination.
Check drain system.
Correct as necessary.
Check induced draft
blower performance.
Correct as necessary.
Correct pressure
switch setpoint or
contact motion.
Tighten or correct
wiring connection.
Check filters and
ductwork for blockage.
Clean filters or remove
obstruction.
Check circulator
blower speed and
performance. Correct
speed or replace
blower if necessary.
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.
Correct short at flame
sensor or in flame
sensor wiring.
Check for lingering
flame.
Verify proper operation
of gas control valve.
Notes and Cautions
Turn off power prior to
repair.
Replace pressure
switch with correct
replacement part.
Turn off power prior to
repair.
Replace pressure
switch with correct
replacement part.
Replace induced draft
blower with correct
replacement part.
Turn off power prior to
repair.
See Specification
Sheet applicable to
your model for
allowable rise range
and proper circulator
speed.
See "Vent/Flue Pipe"
section for piping
details.
Turn off power prior to
repair.
33
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