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T8665A CHRONOTHERM® IV DELUXE PROGRAMMABLE WIRELESS THERMOSTAT
11 69-1535-3
TROUBLESHOOTING GUIDE
For troubleshooting, see Table 6.
Table 6. Troubleshooting Guide.
Symptom Possible Cause Action
Display does not
come on.
Thermostat is not being
powered.
Check if batteries are present and installed correctly.
— If batteries are present and installed correctly, replace thermo-
stat.
Temperature
display is
incorrect.
Room temperature display
has been reconfigured.
Enter Installer Setup number 37 and reconfigure the display.
Thermostat is configured
for °F or °C display.
Enter Installer Setup number 14 and reconfigure the display.
Poor choice of thermostat
location.
Relocate the thermostat.
Temperature
settings do not
change.
(Example:
Cannot set the
heating higher or
the cooling
lower.)
The upper or lower
temperature limits were
reached.
Check the temperature setpoints:
• Heating limits are 40 to 90°F (4.5 to 32°C)
• Cooling limits are 48 to 99°F (7 to 35°C)
The setpoint temperature
range stops were
configured.
Check Installer Setup numbers 34 and 35 and reconfigure the setpoint
stops.
Heating does not
come on.
Thermostat is calling for
heat (flame icon is in
display).
• Troubleshoot the W8665 Receiver Module.
• Troubleshoot the heating equipment.
Thermostat is not calling
for heat (no flame icon is in
display).
• Raise heating setpoint above room temperature.
• Check if the W8665 is set up to receive signals from this thermostat.
— Set up W8665 to receive signals.
Thermostat minimum off
time is activated.
Wait up to five minutes for the system to respond.
System selection is not set
to Heat.
Set system selection to Heat.
Heating setpoint is below
room temperature.
Check heating setpoint. Set heating setpoint to desired temperature.
Cooling does not
come on.
Thermostat minimum off
time is activated.
• Wait up to five minutes for the system to respond.
• Enter Installer Setup number 33. Reconfigure minimum off time
(if required).
System selection is not set
to Cool.
Set system selection to Cool.
Cool setpoint is above
room temperature.
Check cooling setpoint. Set cooling setpoint to desired temperature.
Thermostat is calling for
cool (snowflake is in
display).
• Troubleshoot cooling equipment.
• Troubleshoot W8665 Receiver Module.
Thermostat is not calling
for cool (no snowflake icon
is in display).
• Check if the W8665 is set up to receive signals from the thermostat.
— Set up W8665 to receive signals.
System on
indicator
( = heat,
= cool) is
displayed, but no
warm or cool air
is coming from
the registers.
Fan operation set for 0
(conventional heat) when it
should be set for 1 (electric
heat).
Enter Installer Setup number 2 and reconfigure the fan operation.
Conventional heating
equipment turns on the fan
when the furnace has
warmed up to a setpoint.
Wait a minute after seeing the on indicator and then check the
registers.
Heating or cooling
equipment is not operating.
Verify operation of heating or cooling equipment in self-test.
Thermostat
backlight
appears dim.
Backlight may fade over
the life of the batteries.
• Wait unit Replace Battery indicator is illuminated and replace
batteries.
• Replace batteries now.