| Symptom
| Possible Cause
| Action |
| Display will not come on. |
Thermostat is not being powered. |
- Check if the thermostat is mounted and latched on the wallplate--mount and latch the thermostat on the wallplate.
- Check that C terminal is connected to the system transformer.
- Check for 24 VAC between R and C terminals.
- If missing 24 VAC:
- check if the circuit breaker is tripped--reset the circuit breaker.
- check if the system fuse is blown--replace the fuse.
- check if the furnace door is on correctly to energize the door switch.
- check if any condensate float switches are tripped and properly connected.
- check if the power switch on the HVAC equipment is in the OFF position--set to the On position.
- check wiring between thermostat and HVAC equipment--replace any broken wires and tighten any loose connections.
- If 24 VAC is present, proceed with troubleshooting.
|
| Thermostat display goes blank. |
Thermostat and furnace incorrect interaction. |
Move the common wire from thermostat C terminal on circuit board of the furnace to the common leg of the transformer (by-passing the circuit board for power). |
| Temperature display is incorrect. |
Room temperature display has not 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. |
| Bad thermostat location. |
Relocate the thermostat. |
| Temperature settings will 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 (7 to 31°C)
- Cooling limits are 48 to 99°F (9 to 37°C)
|
| The setpoint temperature range stops were configured. |
Check Installer Setup numbers 34 and 35 and reconfigure the setpoint stops. |
| Heating will not come on. |
No power to the thermostat. |
- Check that C terminal is connected to the system transformer.
- Check for 24 VAC between R and W terminals.
- If missing 24 VAC:
- check if the circuit breaker is tripped--reset the circuit breaker.
- check if the system fuse is blown--replace the fuse.
- check if the power switch on the HVAC equipment is in the Off position--set to the On position.
- check wiring between thermostat and HVAC equipment--replace any broken wires and tighten any loose connections.
- If 24 VAC is present, proceed with troubleshooting.
|
| Heating will not come on. |
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 will not come on. |
No power to the thermostat. |
- Check that C terminal is connected to the system transformer.
- Check for 24 VAC between R and X or RC and Y terminals.
- If missing 24 VAC:
- check if the circuit breaker is tripped--reset the circuit breaker.
- check if the system fuse is blown--replace the fuse.
- check if the power switch on the HVAC equipment is in the Off position--set to the On position.
- check wiring between thermostat and HVAC equipment--replace any broken wires and tighten any loose connections.
- If 24 VAC is present, proceed with troubleshooting.
|
| 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. |
| Heating or cooling come on momentarily and shut off. |
Heat or cool circuit is opening up or becoming high impedance. |
Add resistor in parallel with load or install interface relay. |
|
System on indicator (flame=heat, snowflake=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. |
| Outdoor temperature not displayed* |
Option not activated. |
Enter Installer Setup number 24 and set to 1. Thermostat must have OT terminals and a C7089B1000 installed. |
| Outdoor temperature display is incorrect* |
Outdoor sensor is connected incorrectly. |
Refer to C7089B1000 installation instructions and check wiring between the thermostat and sensor. |
| Wrong sensor. |
Replace sensor with C7089B1000 sensor. |