SERVICING
63
INDOOR UNIT ERROR CODES
Symptoms of Abnormal Operation
(Legacy & ComfortNet™ Thermostat)
7-Segment LED
Codes
Characters
Will Alternat
Fault Description
ComfortNet™
Thermostat Only
Possible Causes Corrective Actions Notes & Cautions
Message Code
• Air handler blower fails to operate
• Integrated control module LED
display provides no signal.
• ComfortNet™ thermostat “Call for
Service” icon illuminated
• ComfortNet™ thermostat scrolls
“Check Air Handler” message
No Display
• No 208/230 volt
power to air handler
blower or no 24 volt
power to integrated
control module
• Blown fuse or circuit
breaker
• Integrated control
module has an
internal fault.
INTERNAL
FAULT
EE
• Manual disconnect switch
OFF or 24 volt wire
improperly connected or
loose
• Blown fuse or circuit breaker
• Integrated control module
has an internal fault
• Assure 208/230 volt and 24
volt power to air handler
blower and integrated
control module.
• Check integrated control
module fuse (3A). Replace
if necessary.
• Check for possible shorts in
208/230 volt and 24 volt
circuits. Repair as
necessary.
• Replace bad integrated
control module.
• Turn power OFF prior
to repair.
• Replace integrated
control module fuse
with 3A automotive
fuse.
• Replace integrated
control module with
correct replacement
part
• Read precautions in
“Electrostatic
Discharge” section of
manual.
• Air handler blower fails to operate.
• Integrated control module LED
display provides indicated error
code.
• ComfortNet™ thermostat “Call for
Service” icon illuminated.
• ComfortNet™ thermostat scrolls
“Check Air Handler” message.
d0
• Data not yet on
network.
NO NET
DATA
d0
• Air handler blower does not
contain any shared data.
• Populate shared data set
using memory card.
• Turn power OFF prior
to repair
• Use memory card for
the specific model.
• Insert memory card
BEFORE turning
power ON. Memory
card may be removed
after data is loaded.
• Error code will be
cleared once data is
loaded.
• Turn power off before
removing memory
card
• Air handler blower fails to operate.
• Integrated control module LED
display provides indicated error
code.
• ComfortNet™ thermostat “Call for
Service” icon illuminated.
• ComfortNet™ thermostat scrolls
“Check Air Handler” message.
d1
• Invalid data on
network.
INVALID
DATA
d1
• Air handler blower does not
contain an appropriate
shared data set.
• Populate correct shared
data set using memory
card.
• Turn power OFF prior
to repair
• Use memory card for
the specific model.
• Insert memory card
BEFORE turning
power ON. Memory
card may be removed
after data is loaded.
• Error code will be
cleared once data is
loaded.
• Operation different than expected or
no operation.
• Integrated control module LED
display provides indicated error
code.
• ComfortNet™ thermostat “Call for
Service” icon illuminated.
• ComfortNet™ thermostat scrolls
“Check Air Handler” 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 specific
model. Re-populate data
using correct memory card
if required.
• Turn power OFF prior
to repair
• Use memory card for
the specific model.
• Insert memory card
BEFORE turning
power ON. Memory
card may be removed
after data is loaded.
• Error code will be
cleared once data is
loaded.
• Turn power off before
removing memory
card