GVZC20 Service Manual
SERVICING
35
INDOOR UNIT TROUBLESHOOTING FOR TXV APPLICABLE UNIT (MBVC**00AA-1)
Symptoms of Abnormal Operation (Legacy &
ComfortNet™Thermostat)
7
-
S
egmen
t
LED
Codes
Characters Will
Alternate
Fault Description Possible Causes Corrective Actions Notes & Cautions
• LED dis
p
la
y
is ON continuousl
y
On • Normal o
p
eration None None • Normal o
p
eration • None • Normal o
p
eration
• Electric heaters fail to energize on a call for
W1 or Auxiliary/ Emergency heat
• Integrated control module LED display
provides the indicated error code.
• ComfortNet™thermostat “Call for Service”
icon illuminated
• ComfortNet™thermostat scrolls “Check Air
Handler” message
EC • Heater kit selected via
dipswitches is too large for
heater kit s specified in
shared
data set
HTR TOO
LARGE
EC • Heater kit selected via
dipswitches is too large for heater
kits in shared data set
• Verify electric heat dipswitch set
tings
• Verify the installed electric heater
is valid for the air handler blower.
Check nameplate or Specification
Sheet applicable to your model* for
allowable heater kit(s).
• Verify shared data set is correct
for the specific model. Re-pop ulate
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
BEFOREturning
power ON. Bluetooth®
Shared Data Loader
BTSDL01 may be removed
after data is loaded.
• Turn power off before
removing Bluetooth® Shared
Data Loader BTSDL01.
• Electric heat airflow is higher than
expected on a call for W1 or
Auxiliary/Emergency heat
• Integrated control module LED display
provides the indicated error code.
EC • Heater kit selected via
dipswitches is too small for
heater kits specified in
shared
data set
HTR TOO
SMALL
EC • Heater kit selected via
dipswitches is too small for heater
kits in shared data set
• Verify electric heat dipswitch set
tings
• Verify the installed electric heater
is valid for the air handler blower.
Check nameplate or Specification
Sheet applicable to your model* for
allowable heater kit(s).
• Verify shared data set is correct
for the specific model. Re-pop ulate
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
BEFOREturning
power ON. Bluetooth®
Shared Data Loader
BTSDL01 may be removed
after data is loaded.
• Turn power off before
removing Bluetooth® Shared
Data Loader BTSDL01.
• Electric heat airflow is higher than
expected on a call for W1 or Auxiliary/
Emergency heat
• Integrated control module LED display
provides the indicated error code.
EC • Heater kit selected via
dipswitches does not
heater kits specified in
shared
data set
NO HTR
MATCH
EC • Heater kit selected via
dipswitches is doesn’t match
heater kits in shared data
set
• Verify electric heat dipswitch set
tings
• Verify the installed electric heater
is valid for the air handler blower.
Check nameplate or Specification
Sheet applicable to your model* for
allowable heater kit(s).
• Verify shared data set is correct
for the specific model. Re-pop ulate
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
BEFOREturning
power ON. Bluetooth®
Shared Data Loader
BTSDL01 may be removed
after data is loaded.
• Turn power off before
removing Bluetooth® Shared
Data Loader BTSDL01.
• Integrated control module LED display EF
error code.
• ComfortNet™thermostat “Call for Service”.
EF • Aux switch open Aux Alarm
Fault
EF • High water level in the
evaporation coil.
• Check overflow pan and service • Turn power OFF prior to
service.
ComfortNet™
Thermostat Only
Message Code