Installation Guide

27
T ROUBLESHOOTING C HART
PCBBF145 CONTROL BOARDS
1
Integrated control module will automatically attempt to reset from lockout after one hour.
2
LED Flash code will cease if power to the control module is interrupted through the disconnect or door switch.
•Furnace lockout due
to an excessive
number of ignition
attempts. (3 total)
1
•Auxiliary Limit Open
•Locate and correct
gas interruption.
•Replace or realign
igniter.
•Check flame sense
signal. Clean sensor if
coated and/or
oxidized.
•Check flue piping for
blockage, proper
length, elbows, and
termination.
•Verify proper induced
draft blower
performance.
•Check circulator
blower speed and
performance. Correct
speed or replace
blower if necessary.
•Turn power OFF
prior to repair.
•Igniter is fragile,
handle with care.
•Clean flame sensor
with steel wool.
•See “Combustion
and Ventilation Air
Requirements” and
“Category I Venting
(Vertical Venting)”
section for details.
•See Product Data
Bulletin for
allowable rise
range and proper
circulator speed.
•Furnace fails to operate.
•Integrated control
module diagnostic LED is
flashing ONE (1) flash.
1
1 FLASH
•Failure to establish flame.
Cause may be no gas to
burners, bad igniter or
igniter alignment,
improper orifices, or
coated/oxidized or
improperly connected
flame sensor.
•Loss of flame after
establishment. Cause may
be interrupted gas supply,
lazy burner flames
(improper gas pressure or
restriction in flue or
improper induced draft
blower performance.
•Insufficient conditioned air
over the heat exchanger.
Blocked filters, restrictive
ductwork, improper
circulator blower speed, or
failed circulator blower.
•Main power interruption
during heat cycle causing
auxiliary limit to open.
•Pressure switch
circuit is closed.
•Induced draft blower
is not operating.
•Replace induced
draft blower pressure
switch.
•Repair short.
•Turn power OFF
prior to repair.
•Replace pressure
switch with proper
replacement part.
•Furnace fails to operate.
•Integrated control
module diagnostic LED is
flashing TWO (2) flashes.
2
2 FLASHES
•Induced draft blower
pressure switch contacts
sticking.
•Shorts in pressure switch
circuit.
•Inspect pressure switch
hose. Repair, if necessary,
•Inspect flue for blockage,
proper length, elbows,
and termination.
•Correct pressure switch
setpoint or contact
motion.
•Tighten or correct wiring
connection.
•Inspect masonry chimney
and flue; remove
blockage.
•Pressure switch hose
blocked, pinched or
connected improperly.
•Blocked flue or weak
induced draft blower.
•Incorrect pressure switch
setpoint or malfunctioning
switch contacts.
•Loose or improperly
connected wiring.
•Blockage in flue or chimney.
•Pressure switch
circuit not closed.
•Induced draft blower
is operating.
•If installed, manual
reset limit switch is
open on Masonry
Vent Kit (MVK).
•Induced draft blower
runs continuously with
no further furnace
operation.
•Integrated control
module diagnostic LED
is flashing THREE (3)
flashes.
3
3 FLASHES
•Turn power OFF prior
to repair.
•See “Combustion and
Ventilation Air
Requirements” and
“Category I Venting
(Vertical Venting)”
section for details.
•Replace pressure
switch with proper
replacement part.
•Replace masonry
vent kit limit switch
with correct
replacement part.
•Integrated control
module has an
internal fault.
•Integrated control module
has an internal fault.
•Turn power OFF
prior to repair.
•Read precautions
in “Electrostatic
Discharge” section
of manual.
•Furnace fails to operate.
•No 115 volt power to
furnace, or no 24 volt
power to integrated
control module.
•Blown fuse or circuit
breaker.
•Manual disconnect switch
OFF, door switch open, or 24
volt wires improperly
connected or loose.
•Blown fuse or circuit breaker.
•Assure 115 and 24 volt
power to furnace
integrated control
module.
•Check for possible shorts
in 115 and 24 volt circuits.
Repair as necessary.
•Replace bad integrated
control module.
•Turn power OFF
prior to repair.
•Furnace fails to operate.
•Integrated control
module diagnostic LED
provides no signal.
NONE
Cautions
& Notes
Corrective
Action
Possible
Causes
Fault
Description(s)
Symptoms of
Abnormal Operation
Associated
LED Code
2