Section 7.Troubleshooting
Symptom
Possible Causes
Action
Thermostat displays an alert
code on the screen.
Alert Code is present.
Refer to the Alert Code Addendum. Check the
Alert icons in the diagnostic screen.
Display will not come on
Loss of 24VAC between R & B at the thermo-
stat.
1) Check wiring between R & B to see if R & D, or
B & D have been reversed.
2) Check transformer for 24VAC output.
3) Check for broken or shorted thermostat wire.
Indoor temperature display is
incorrect.
Indoor temperature display needs calibration.
Indoor humidity display needs calibration.
1) Oversized heating/cooling equipment under
Calibrate temperature sensor from thermostat
menu.
Indoor humidity display is incor-
rect.
Calibrate humidity sensor from the thermostat
menu.
Room temperature overshoots
when the Heat/Cool setting is
changed more than 2°.
1) Compare heat load calculation to equipment
current conditions. Control cannot respond fast chosen.
enough to prevent overshooting.
2) Improper location of thermostat.
3) Aggressive recovery is activated.
2) Relocate thermostat (or use remote sensor) if
thermostat is in “dead” spot (poor or no air circula-
tion).
3) Deactivate aggressive recovery.
Heating will not come on.
Cooling will not come on.
Heating or Cooling is displayed,
1) System mode is not set to heat/Auto or set-
point is set too low.
2) Minimum off time delay is being enforced.
3) Heating system may require service.
1) Set mode to heat and raise the setpoint above
the room temperature.
2) Wait for 5 minutes and recheck heating equip-
ment.
3) Check/repair system.
1) System mode is not set to cool/Auto or the
setpoint is too high.
2) Minimum off time delay is being enforced.
3) Cooling system may require service.
1) Set mode to cool and lower the setpoint below
the room temperature.
2) Wait for 5 minutes and recheck cooling equip-
ment.
3) Check/repair system.
1) There is a fan delay as the heating or cooling 1) Wait a minute for blower delays and recheck
but no warm or cool air is coming equipment turns on.
registers.
from the registers.
2) Equipment is not working properly.
2) Check/repair system.
Fan runs all the time
1) Fan mode is set to On, Circulate or Clean
mode
1) Check thermostat settings to see if fan is set to
On, Circulate or Clean mode.
2) There is a failure in the indoor unit
2) Check indoor unit for failures (such as tripped
heating limit).
Fan is set to ON but not running. 1) Humidity control is engaged.
2) Blower motor is not functioning.
1) If indoor humidity is higher than desired set-
point, the blower will cycle off with the equipment.
2) Check/repair system.
Cooling or Heating cycles too
fast or too slow (narrow or wide
temperature swings).
1) Check the location of the thermostat for
drafts.
2) Cycles per hour or aggressive recovery is
improperly set.
1) Seal all air leaks behind thermostat. Relocate
thermostat or apply remote indoor temperature
sensor.
2) Adjust cycle rates and aggressive recovery
features in the advanced installer set up.
Heat pump is not turning on; only 1) Outdoor temperature is below compressor
furnace or electric heat strips are lockout temperature setting.
1) Check/repair outdoor sensor or wiring.
2) Adjust the compressor lockout temperature
setting if desired.
running.
2) Compressor heating lockout is enabled and
outdoor temp sensor is out of calibration or
failed.
Cannot change system mode to
desired setting.
Equipment is not configured properly.
Check the standard installer set up screen to
ensure equipment is properly configured.
Screen does not respond prop-
erly to a button press
Screen is out of calibration
Remove thermostat from sub base and reset.
Follow the calibration instructions when the ther-
mostat reboots.
“No System Found” displayed on Internal error
the thermostat
Reboot the thermostat via onscreen button.
Slow or no response to any but-
ton presses
Internal error
Remove the thermostat from the sub base and
reset.
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