GVZC20 Service Manual
SERVICING
37
INDOOR UNIT TROUBLESHOOTING FOR TXV APPLICABLE UNIT (MBVC**00AA-1)
Message Code
• 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.
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.
• Failed circulator blower motor.
• Tighten or correct wiring connection.
• Check circulator blower motor.
Replace if necessary.
• Turn power OFF prior to repair
• Replace circulator motor with
correct replacement part.
• 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.
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.
• 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.
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 air
handler blower.
• Incorrect shared data set in integrated
control module.
• Verify circulator blower motor horse
power is the same specified for the
specific air handler blower model.
Replace is necessary.
• 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
• Replace motor with correct
replacement part.
• 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
shared data and motor horse
power match.
• Turn power off before removing
Bluetooth® Shared Data Loader
BTSDL01
• Air handler blower operates at reduced
performance.
• Airflow 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 filters.
• Restrictive ductwork.
• Undersized ductwork.
• High ambient temperatures.
• Check filters for blockage. Clean
filters 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 "Installation Instructions" for
installation requirements.
• Turn power OFF prior to repair.
• 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” messa
g
e.
b4
• Circulator blower motor
senses a loss rotor control.
• Circulator blower motor
senses high current.
MOTOR
TRIPS
b4
• Abnormal motor loading, sudden
change in speed or torque, sudden
blockage of air handler blower/coil air
inlet or outlet.
• High loading conditions, blocked filters,
very restrictive ductwork, blockage of air
• Check filters, filter grills/registers,
duct system, and air handler blower/coil
air inlet/outlet for blockages.
• Turn power OFF prior to repair.
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