76
Troubleshooting
ComfortNet
Thermostat Only
Symptoms of Abnormal Operation
(Non-communicating & ComfortNet™
Thermostat)
Diagnostic/Status
LED Codes
Fault Description
Message Code
Possible Causes
Corrective Actions
Notes & Cautions
x Circulator blower runs continuously. No
furnace operation.
x Integrated control module LED display
provides
error code.
x ComfortNet thermostat “Call for Service”
icon illuminated.
x ComfortNet thermostat scrolls “Check
Furnace” message.
E3
x Primary limit.
HIGH
LIMIT
OPEN
E3
x Insufficient conditioned air over
the heat exchanger. Blocked
filters, restrictive ductwork,
improper circulator blower speed,
or failed circulator blower motor.
x Loose or improperly connected
wiring.
x Check filters and ductwork for
blockage. Clean filters or
remove obstruction.
x Check circulator blower speed
and performance. Correct speed
or replace blower motor if
necessary.
x Tighten or correct wiring
connection.
x Turn power OFF prior to
repair.
x See Specification Sheet
applicable to your model
for allowable rise range
and proper circulator
speed.
x Induced draft blower and circulator blower
runs continuously. No furnace operation.
x Integrated control module LED display
provides
error code.
x ComfortNet thermostat “Call for Service”
icon illuminated.
x ComfortNet thermostat scrolls “Check
Furnace” message.
E4
x Flame sensed when it
should not be present.
IMPROPER
FLAME
E4
x Short to ground in flame sense
circuit.
x Lingering burner flame.
x Slow closing gas valve.
x Correct short at flame sensor or
in flame sensor wiring.
x Check for lingering flame.
x Verify proper operation of gas
valve. Replace if necessary.
x Turn power OFF prior to
repair.
x Furnace fails to operate
x Integrated control module LED display
provides EC error code.
x ComfortNet thermostat “Call for Service”
icon illuminated.
x ComfortNet thermostat scrolls “Check
Furnace” message.
EC
x Inducer motor
overcurrent fault.
INDUCER
FAULT
OR
INDUCER
LOCKOUT
EC
x Lingering Inducer motor
overcurrent detected.
x Reset system power and verify
inducer is running properly.
x Replace inducer or integrated
control module, if necessary.
x No furnace operation.
x Integrated control module LED display
provides
d error code.
Ed
x Manual reset rollout
switch is open
ROLLOUT
OPEN
Ed
x Orifice plate out of position.
x Blocked heat exchanger.
x Burners out of alignment.
x Defective heat exchanger.
x Line up orifice plate.
x Remove Blockage from heat
exchanger.
x Line up burners.
x Check for flame disturbance on
roll out when blower comes on.
x Turn power OFF prior to
repair.
x No furnace operation.
x Integrated control module LED display
provides Ef error code.
EF
x Open auxiliary input.
AUXILIARY
OPEN
EF
x Open circuit between aux in or
aux out.
x Missing jumper.
x Open float switch..
x Install jumper.
x Inspect float switch.
x Turn power OFF prior to
repair.
x No furnace operation.
x Integrated control module LED display
provides
error code.
x ComfortNet thermostat displays “Battery
Power”.
E5
x Open Fuse
Not
Displayed
Not
Displayed
x Short in low voltage wiring x Locate and correct short in low
voltage wiring
x Turn power OFF prior to
repair.
x Replace fuse with 3-amp
automotive type
x Normal furnace operation.
x Integrated control module LED display
provides
error code.
E6
x Flame sense micro amp
signal is low
WEAK
FLAME
E6
x Flame sensor is coated/oxidized.
x Flame sensor incorrectly
.positioned in burner flame.
x Lazy burner flame due to
improper gas pressure or
combustion air.
x Clean flame sensor if
coated/oxidized.
x Inspect for proper sensor
alignment.
x Check inlet air piping for
blockage, proper length, elbows,
and termination.
x Compare current gas pressure to
rating plate. Adjust as needed.
x Turn power OFF prior to
repair.
x Clean flame sensor with
steel wool.
x See "Vent/Flue Pipe"
section for piping details.
x See rating plate for proper
gas pressure.
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