If you want to perform Trane thermostat troubleshooting, use one of the tables from this page: they provide step-by-step fixing instructions for the most popular Trane thermostat models. Each manual enlists the most widespread technical failures, suggests possible causes and instructs on how to solve the problem. Error alert codes are also explained.
| Symptom | Possible Cause | Action |
|---|---|---|
| Display will not come on | Loss of 24VAC between R & C at the Control | 1) Check wiring between R & C |
| 2) Check transformer for 24VAC output | ||
| 3) Check for broken or shorted thermostat wire | ||
| Indoor Temperature display is incorrect | 1) Indoor temperature display needs calibrating (always allow 1 hour before calibrating after any power cycle) | 1) Calibrate indoor temperature sensor |
| 2) Heat from the touchscreen is being trapped within the body of the control | 2) Relocate the control away from any competing air sources or redirect the air sources away from the control | |
| Indoor humidity display is incorrect | Indoor humidity sensor needs calibrating | Calibrate humidity sensor |
| Room temperature overshoots the desired setpoint in cooling mode | 1) The delta ‘Off in cooling mode is set to a negative number | 1) Intended operation; if objectionable, change the delta “Off” to 0 degrees |
| 2) Cooling overshoot is enabled and the indoor RH is higher than the target cooling RH | 2) Intended operation: if objectionable, disable cooling over- shoot or raise cooling target RH | |
| 3) Minimum compressor on time has not been met | 3) Intended operation; if objectionable, lower minimum on time (lowest setting available is 3 minutes) | |
| Room temperature overshoots the desired setpoint in heating mode | 1) The delta ‘Off in heating mode is set to a positive number | 1) Intended operation; if objectionable, change the delta “OfT’ to 0 degrees |
| 2) Minimum compressor/indoor heat on time has not been met | 2) Intended operation; if objectionable, lower the minimum on time (lowest setting available is 3 minutes) | |
| Cooling will not come on | 1) System mode is not set to Cool/Auto or setpoint is set too high | 1) Select the correct system mode and/or lower the setpoint |
| 2) Delta “On” for cooling is set too high | 2) Change the delta “On” setting for cooling mode | |
| 3) Minimum off time delay is being enforced | 3) Intended operation; if objectionable, lower the minimum off time delay (lowest setting is 5 minutes) | |
| 4) Cooling system may need service | 4) Check/repair system | |
| Heating will not come on | 1) System mode is not set to Heat/Auto or setpoint is set too low | 1) Select the correct system mode and/or raise the setpoint |
| 2) Delta “On” for heating is set too high | 2) Change the delta “On” setting for heating mode | |
| 3) Minimum off time delay is being enforced | 3) Intended operation; if objectionable, lower the minimum off time delay (lowest setting is 5 minutes) | |
| 4) Heating system may need sen/ice | 4) Check/repair system | |
| Heating or Cooling is being displayed, but no air coming from registers/ vents | 1) Fan delay time has not expired | 1) Wait one minute for blower delay to end, then recheck register/grills |
| 2) System is not operating properly | 2) Check/repair system | |
| Fan runs all the time | 1) Fan mode is set to “On’ or “Circ” | 1) Intended operation; if objectionable, change fan mode to “Auto” |
| 2) System is not operating properly | 2) Check/repair system | |
| Fan is set to “On” but not running | 1) Smart continuous fan is enabled and the indoor humidity is higher than the cooling target RH (SCF will be displayed on fan mode button) | 1) Intended operation; if objectionable, disable SCF or raise cooling target humidity |
| 2) System is not operating properly | 2) Check/repair system |
| Symptom | Action |
|---|---|
| Heating or Cooling will not come on. | Check that the SYSTEM switch on the thermostat is set to Heat or Cool. |
| Check if the circuit breaker is tripped—reset the circuit breaker. | |
| Check if the fuse is blown— replace the fuse. | |
| Check for air movement at the register. | |
| Check power to the heating or cooling equipment. | |
| Temperature setting is too warm or cool. | Adjust the temperature by pressing either the ▲ or ▼ key. |
| Error code | Solution |
|---|---|
| LED 1 Green: System Operation display: Sys Off displayed | HVAC system is OFF |
| LED 1 Green: System Operation display: WAIT displayed | Minimum Off Time (MOT)delay is active; LED Off |
| LED 1 Green: System Operation display: Cool On displayed | Cooling system is running; LED On |
| Cooling Min Run Time (MRT); LED On | |
| LED 1 Green: System Operation display: Heat On displayed | Heating system is running; LED On |
| Heating Minimum Run Time (MRT); LED On | |
| LED 2 Green: System Stage display: No display | 1st stage heating or cooling. LED Off |
| LED 2 Green: System Stage display: 2nd Stg displayed | Stage 2 heating or cooling is active. LED On |
| LED 2 Green: System Stage display: Aux Heat displayed | Stage 3 heating is active. LED On |
| LED 3 Green: Run/Hold/ESM display. Shows state of Schedule Run/Hold Mode: Hold displayed | Temperature hold is active. LED On |
| LED 3 Green: Run/Hold/ESM display. Shows state of Schedule Run/Hold Mode: ESM displayed | (Energy Savings Mode) Temperature preset is active. LED On |
| LED 4 RED: Alert LED. Used for other system alerts: No display | No alerts or messages. LED Off |
| LED 4 RED: Alert LED. Used for other system alerts: Filter displayed | Filter run timer reached. LED On |
| LED 4 RED: Alert LED. Used for other system alerts: Maint displayed | Maintenance run timer reached. LED On |
| Symptom | Possible Cause | Action |
|---|---|---|
| Display does not come on. | Comfort control is not being powered. | Check for 24 Vac between B and Rc. |
| Temperature settings do not change. | The upper or lower temperature limits were reached. | Check temperature setpoints. |
| Check Installer Setup Numbers 0600 and 0610; modify as needed. | ||
| The keypad is fully locked. | Check Installer Setup Number 0670 to change keypad locked options. | |
| Heating or cooling does not come on. | Comfort control minimum off- time is activated. | Wait up to five minutes for the system to respond. |
| System selection is not set to Heat or Cool. | Set system Selection to correct position. | |
| System type Selection is incorrect. | Check Installer Setup Number 0170 and make sure correct System type is chosen. | |
| Comfort control is calling for Heat (Heat on) or Cool (Cool on) but no heating or cooling is running. | Heating or cooling equipment is not operating. | Check wiring. |
| Check Installer Setup Number 0170 and make sure correct system type is chosen. Verify operation of equipment in System Test mode. | ||
| Comfort control does not respond when touch areas are pressed. | The keypad is locked. | Check Installer Setup Number 0670 to change keypad locked options. |
| Symptom | Possible Causes | Action |
|---|---|---|
| Thermostat displays an alert code on the screen. | Alert Code is present. | 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. | Calibrate temperature sensor from thermostat menu. |
| Indoor humidity display is incor- rect. | Indoor humidity display needs calibration. | Calibrate humidity sensor from the thermostat menu. |
| Room temperature overshoots when the Heat/Cool setting is changed more than 2°. | 1) Oversized heating/cooling equipment under current conditions. Control cannot respond fast enough to prevent overshooting. | 1) Compare heat load calculation to equipment chosen. |
| 2) Improper location of thermostat. | 2) Relocate thermostat (or use remote sensor) if thermostat is in “dead” spot (poor or no air circulation). | |
| 3) Aggressive recovery is activated. | 3) Deactivate aggressive recovery. | |
| Heating will not come on. | 1) System mode is not set to heat/Auto or set- point is set too low. | 1) Set mode to heat and raise the setpoint above the room temperature. |
| 2) Minimum off time delay is being enforced. | 2) Wait for 5 minutes and recheck heating equipment. | |
| 3) Heating system may require service. | 3) Check/repair system. | |
| Cooling will not come on. | 1) System mode is not set to cool/Auto or the setpoint is too high. | 1) Set mode to cool and lower the setpoint below the room temperature. |
| 2) Minimum off time delay is being enforced. | 2) Wait for 5 minutes and recheck cooling equipment. | |
| 3) Cooling system may require service. | 3) Check/repair system. | |
| Heating or Cooling is displayed, but no warm or cool air is coming from the registers. | 1) There is a fan delay as the heating or cooling equipment turns on. | 1) Wait a minute for blower delays and recheck 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. | 1) If indoor humidity is higher than desired set- point. the blower will cycle off with the equipment. |
| 2) Blower motor is not functioning. | 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. | 1) Seal all air leaks behind thermostat. Relocate thermostat or apply remote indoor temperature sensor. |
| 2) Cycles per hour or aggressive recovery is improperly set. | 2) Adjust cycle rates and aggressive recovery features in the advanced installer set up. |