Specifications

40
■ Induced draft blower runs
continuously with no
further furnace operation.
■ Integrated control module
diagnostic LED is flashing
3flashes.
3 flashes
■ Pressure switch circuit not closed.
■ Induced draft blower is operating.
■ Pressure switch hose blocked, pinched
or 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.
■ Inspect pressure switch hose. Repair, if
necessary,
■ Inspect flue and/or inlet air piping for
blockage, proper length, elbows, and
termination. Check drain system. Correct
as necessary.
■ Correct pressure switch setpoint or
contact motion.
■ Tighten or correct wiring connection.
■ Circulator blower runs
continuously. No furnace
operation.
■ Integrated control module
diagnostic LED is flashing
4flashes.
4 flashes
■ Primary or auxiliary limit circuit is open
or faulty.
■ Insufficient conditioned air over the
heat exchanger. Blocked filters,
restrictive ductwork, improper
circulator blower speed or failed
circulator blower.
■ Loose or improperly connected wiring.
■ Check primary limit switch. 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.
■ Induced draft blower and
circulator blower runs
continuously. No furnace
operation.
■ Integrated control module
diagnostic LED is flashing
5flashes.
5 flashes
■ Flame sensed with no call for heat.
■ Short to ground in flame sensor circuit.
■ Correct short at flame sensor or in flame
sensor wiring.
■ Furnace fails to operate.
■ Integrated control module
diagnostic LED is flashing
6flashes.
6 flashes ■ Rollout limit switch open.
■ Integrated control module fuse is
blown.
■ Flame rollout.
■ Misaligned burners, blocked flue
and/or air inlet pipe or failed induced
draft blower.
■ Loose or improperly connected wiring.
■ Short in 24-volt AC control circuits or
safety circuits.
■ Faulty rollout limit switch.
■ Check burners for proper alignment.
■ Check flue and air inlet piping for
blockage, proper length, elbows and
termination. Correct as necessary. See
“Vent/Flue Pipe.”
■ Check rollout limit switch. Replace, if
necessary.
■ Check induced draft blower for proper
performance. Replace, if necessary.
■ Tighten or correct wiring connection.
■ Repair short in 24-volt AC control/safety
circuit(s).
■ Replace integrated control module fuse
(3A).
■ Normal furnace operation.
■ Integrated control module
diagnostic LED is flashing
7flashes.
7 flashes ■ Flame sensor microamp signal is low.
■ Flame sensor is coated/oxidized.
■ Flame sensor incorrectly positioned in
burner flame.
■ Lazy burner flame due to improper gas
pressure or combustion air.
■ Sand flame sensor with emery cloth.
■ Inspect for proper sensor alignment.
■ Compare current gas pressure to rating
plate info. Adjust as needed.
■ Furnace not operating.
■ Integrated control module
diagnostic LED is flashing
8flashes.
8 flashes
■ Problem with igniter circuit. Improperly
connected igniter. Bad igniter.
■ Poor unit ground.
■ Poor burner ground.
■ Faulty integrated control module.
■ Check and correct wiring from integrated
control module to igniter
■ Replace bad igniter.
■ Check and correct unit ground wiring.
■ Replace bad integrated control module.
■ Induced draft blower runs
continuously. Furnace
fails to operate.
■ Integrated control module
diagnostic LED is flashing
continuously.
Continuous
flashes
■ Polarity of 115-volt or 24-volt power is
reversed.
■ Polarity of 115-volt AC power to
furnace or integrated control module is
reversed.
■ Red and blue wires to transformer are
reversed.
■ Poor unit ground.
■ Review wiring diagram to correct polarity.
■ Verify proper ground. Correct if
necessary.
■ Reverse red and blue wires connected to
transformer.
Problem LED Code Fault/Cause Solution