GVZC20 Service Manual
SERVICING
38
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” messa
g
e.
b5
• Circulator blower motor fails
to start 10 consecutive times.
MTR LCKD
ROTOR
b5
• Obstruction in circulator blower
housing.
• Seized circulator blower motor
bearings.
• Failed circulator blower motor.
• Check circulator blower for
obstructions. Remove and
repair/replace wheel/motor if
necessary.
• Check circulator blower motor shaft
rotation and motor. Replace motor if
necessary.
• Turn power OFF prior to repair
• Replace motor with correct
replacement part.
• Replace wheel 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” messa
g
e.
b6
• Circulator blower motor shuts
down for over or under voltage
condition.
• Circulator blower motor shuts
down due to over temperature
condition on power
module.
MOTOR
VOLTS
b6
• High AC line voltage to air handler
blower.
• Low AC line voltage to air hander
blower.
• High ambient temperatures.
• Check power to air handler blower.
Verify line voltage to blower is within the
range specified on the air handler
blower rating plate.
• 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” message.
b7
• Circulator blower motor does
not have enough information to
operate properly. Motor fails to
start 40 consecutive times.
MOTOR
PARAMS
b7
• Error with integrated control module.
• Motor has a locked rotor condition.
• Check integrated control module.
Verify control is populated with correct
shared data set. See data errors above
for details.
• Check for locked rotor condition (see
error code above for details).
• Turn power OFF prior to repair.
• Replace with correct
replacement part(s).
• 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
• Turn power off before removing
Bluetooth® Shared Data Loader
BTSDL01.
• Air handler blower operates at reduced
performance or operates on low stage when high
stage is expected.
• Integrated control module LED display provides
indicated error code.
b9
• Airflow is lower than
demanded.
LOW ID
AIRFLOW
b9
• Blocked filters.
•
Restrictive ductwork.
• Undersized ductwork.
• 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.
• 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