16
Clock
Operational and connection information
Factory Conguration Mode
Press zone (   ) and mode (M) buttons at a time for 10 
seconds to enter into the factory conguration mode. 
When this setting is rst selected, 799 shall be displayed 
in the temperature-zone and an initial value of 10 shall be 
displayed in the time-zone of the display. Press and hold 
the down button. When the counter reaches zero, “Fd” shall 
be displayed in the temperature-zone of the display. This 
represents factory defaults are in progress. Upon successful 
completion of restoring
defaults to EEPROM, the NUI shall then force a reset.
The clock will continue to operate for 8 hours while power 
is removed.
Room Air Temperature Sensor Failure:
If the sensor used to sense room air temperature reads 
less than -45°C or greater than 65°C, it shall be considered 
failed. If it has been agged as failed, the room temperature 
displays will show “--”.
Humidity Sensor Failure:
If the sensor used to sense room Humidity reads less than 
0 HR% or greater than 99 HR%, it shall be considered failed. 
If it has been agged as failed, the Humidity displays will 
show “--”.
EEPROM Failure:
If the thermostat non-volatile memory (EEPROM) has failed, 
an “E4” error shall be shown in the room air temperature 
display. When this error is present and power is cycled to 
the thermostat all of the installer congurations, program 
schedule settings
and user settings will be factory default values. This may 
result in incorrect equipment operation. There is no eld x 
for this error. The thermostat must be replaced.
Communication Failure
If the NUI does not receive CCN communications from the 
main user interface for 60 seconds, the display will show 
“E3” error code in the Temperature display area and ‘-‘in all 
the Time Display Area. Under this condition the outside 
temperature will be blanked.
“E3” error code will be displayed once and the other 
functionality will remain same. If this happens then check 
the communication cable between NUI and outdoor unit.
Error Codes
English