Installation Guide

51
T ROUBLESHOOTING C HART
Symptoms of Abnormal
Operation (Legacy
& ComfortNet™
Thermostat)
Diagnostic/
Status LED
Codes
Fault Description
ComfortNet™
Thermostat Only
Possible Causes Corrective Actions Notes & Cautions
Message Code
• Operation different than
expected or no operation.
• Integrated control
module LED display
provides d4 error code.
• ComfortNet™ thermostat
“Call for Service” icon
illuminated.
• ComfortNet™ thermostat
scrolls “Check Furnace”
message.
d4 • Invalid memory
card data.
INVALID MC
DATA
d4 • Shared data set on
memory card has been
rejected by integrated
control module
• Verify shared data set is
correct for the specifc
model. Re-populate data
using correct memory
card if required.
• Turn power OFF prior
to repair
• Use memory card for
the specifc model.
• Insert memory card
BEFORE turning
power ON. Memory
card may be removed
after data is loaded
and power is turned
off.
• Error code will be
cleared once data is
loaded and power is
turned off.
• Furnace fails to operate.
• Integrated control
module LED display
provides b0 error code.
• ComfortNet™ thermostat
“Call for Service” icon
illuminated.
• ComfortNet™ thermostat
scrolls “Check Furnace”
message.
b0 • Circulator blower
motor is not
running when it
should be running.
MOTOR NOT
RUN
b0 • Loose wiring connection
at circulator motor
power leads or
circulator motor power
leads disconnected.
• Open circuit in inductor
or loose wiring
connection at inductor
(3/4 Hp and 1 Hp
models only).
• Failed circulator blower
motor.
• Tighten or correct wiring
connection.
• Verify continuous
circuit through inductor.
Replace if open or short
circuit.
• Check circulator blower
motor. Replace if
necessary.
• Turn power OFF prior
to repair
• Replace inductor with
correct replacement
part.
• Replace circulator
motor with correct
replacement part.
• Furnace fails to operate.
• Integrated control
module LED display
provides b1 error code.
• ComfortNet™ thermostat
“Call for Service” icon
illuminated.
• ComfortNet™ thermostat
scrolls “Check Furnace”
message.
b1 • Integrated control
module has lost
communications
with circulator
blower motor.
MOTOR
COMM
b1 • Loose wiring connection
at circulator motor
control leads.
• Failed circulator blower
motor.
• Failed integrated control
module.
• Tighten or correct wiring
connection.
• Check circulator blower
motor. Replace if
necessary.
• Check integrated control
module. Replace if
necessary.
• Turn power OFF prior
to repair
• Replace circulator
motor with correct
replacement part.
• Replace integrated
control module with
correct replacement
part.
• Furnace fails to operate.
• Integrated control
module LED display
provides b2 error code.
• ComfortNet™ thermostat
“Call for Service” icon
illuminated.
• ComfortNet™ thermostat
scrolls “Check Furnace”
message.
b2 • Circulator blower
motor horse
power in shared
data set does not
match circulator
blower motor
horse power.
MOTOR
MISMATCH
b2 • Incorrect circulator
blower motor in furnace.
• Incorrect shared data
set in integrated control
module.
• Verify circulator blower if
motor horse power is the
same specifed for the
specifc furnace model.
Replace if necessary.
• Verify shared data set is
correct for the specifc
model. Re-populate data
using correct memory
card if required.
• Turn power OFF prior
to repair
• Replace motor with
correct replacement
part.
• Use memory card for
the specifc model
• Insert memory card
BEFORE turning
power ON. Memory
card may be removed
after data is loaded
and power is turned
off.
• Error code will be
cleared once shared
data and motor horse
power match.
• Furnace operates at
reduced performance.
• Airfow delivered is less
than expected.
• Integrated control
module LED display
provides b3 error code.
b3 • Circulator blower
motor is operating
in a power,
temperature, or
speed limiting
condition.
MOTOR
LIMITS
b3 • Blocked flters.
• Restrictive ductwork.
• Undersized ductwork.
• High ambient
temperatures.
• Check flters for
blockage. Clean flters
or remove obstruction.
• Check ductwork for
blockage. Remove
obstruction. Verify all
registers are fully open.
• Verify ductwork is
appropriately sized for
system. Resize/replace
ductwork if necessary.
• See "III. Product
Description" and "IV.
Location Requirements
& Considerations"
furnace installation
requirements.
• Turn power OFF prior
to repair.