GVZC20 Service Manual
SERVICING
36
INDOOR UNIT TROUBLESHOOTING FOR TXV APPLICABLE UNIT (MBVC**00AA-1)
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
Bluetooth® Shared Data Loader
BTSDL01.
• Turn power OFF prior to
repair
• Use Bluetooth® Shared
Data Loader BTSDL01 for the
specific model.
• Insert Bluetooth® Shared
Data Loader BTSDL01
BEFORE turning power ON.
Bluetooth® Shared Data
Loader BTSDL01 may be
removed after data is loaded.
• Error code will be cleared
once data is loaded.
• Turn power off before
removing Bluetooth® Shared
Data Loader BTSDL01
• 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 Bluetooth® Shared Data
Loader BTSDL01.
• Turn power OFF prior to
repair
• Use Bluetooth® Shared
Data Loader BTSDL01 for the
specific model.
• Insert Bluetooth® Shared
Data Loader BTSDL01
BEFORE turning power ON.
Bluetooth® Shared Data
Loader BTSDL01 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 Bluetooth® Shared
Data Loader BTSDL01 data.
INVALID
MC DATA
d4 • Shared data set on Bluetooth®
Shared Data Loader BTSDL01 has
been rejected by integrated control
module
• Verify shared data set is correct
for the specific model. Re-populate
data using correct Bluetooth®
Shared Data Loader BTSDL01 if
required.
• Turn power OFF prior to
repair
• Use Bluetooth® Shared
Data Loader BTSDL01 for the
specific model.
• Insert Bluetooth® Shared
Data Loader BTSDL01
BEFORE turning power ON.
Bluetooth® Shared Data
Loader BTSDL01 may be
removed after data is loaded.
• Error code will be cleared
once data is loaded.
• Turn power off before
removing Bluetooth® Shared
Data Loader BTSDL01
Notes & Cautions
Symptoms of Abnormal Operation
(Legacy & ComfortNet™ Thermostat)
7-Segment LED
Codes Characters
Will Alternate
Fault Description
ComfortNet™
Thermostat Only
Possible Causes Corrective Actions