Each table below is a troubleshooting manual for different models of American Standard thermostat: they cover all basic problems with devices and provide all possible solutions to solve the issues. With these tables, a user can check out what might have caused the malfunction, and fix it on one’s own. Please, note that some guidelines are general, and professional help can be required.
| Problem | Cause | Solution |
|---|---|---|
| Display will not come on. | 1. Blown fuse or tripped circuit breaker. | 1. Replace fuse or reset breaker. |
| 2. Furnace power switch OFF. | 2. Turn switch to ON. | |
| 3. Furnace blower compartment door or panel loose or not properly installed. | 3. Replace door panel in proper position to engage safety interlock or door switch. | |
| 4. 360 ohm resistor not installed. | 4. Install 360 ohm – 5 watt resistor | |
| Display comes on and goes off. | 360 ohm resistor not installed. | Install 360 ohm – 5 watt resistor |
| Temperature display is incorrect. | Temperature display needs calibration. | Calibrate Sensor |
| Cannot set Heating setpoint above 80 degrees | Deadband between Heating and Cooling set to high | Decrease Deadband setting |
| Service indicator Flashing on and off. | Control EEPROM write error. | Press any key and Check / Re-enter Setup Choices. |
| Service indicator solid on and in temperature display. | Indoor temperature sensor open or shorted | Replace Control |
| Temperature setting will not change. (Example: Cannot set heating higher or cooling lower). | 1. Upper and/or lower temperature limits were reached. | 1. Check the temperature setpoints: |
| 2. “Keypad locked” is displayed on LCD. | Heating limits are 40 – 85F. | |
| Cooling limits are 65 – 90F. | ||
| 2. Unlock keypad – press Up+Down arrow together until icon disappears. | ||
| Room temperature overshoots when Energy Savings Key ($) is used or the Heat/Cool settings is changed more than 2 degrees. | Oversized heating or cooling equipment. Control can not respond fast enough to prevent overshooting. | Set Control Response rate to “Fast” |
| Heating will not come on. | 1. System Mode not set to Heat. | 1. Set Mode to heat and raise the setpoint above room temperature. |
| 2. Minimum off time delay being enforced. | 2. If heating does not come on within 5 minutes, Check Heating. | |
| 3. Loose connection to control or system. | 3. Check / Repair connections. | |
| 4. Heating system requires service or control requires replacement. | 4. Repair system / Replace control. | |
| Cooling will not come on. | 1. System Mode not set to Cool. | 1. Set Mode to cool and lower the setpoint below room temperature. |
| 2. Minimum off time delay being enforced | 2. If cooling does not come on within 15 minutes, contact servicer. | |
| 3. Loose connection to control or system. | 3. Repair connections. | |
| 4. Cooling system requires service or control requires replacement. | 4. Repair system / Replace control. | |
| Cool ON or Heat ON is displayed, but no warm or cool air is coming from the registers. | 1. The heating equipment turns on the | 1. Wait one minute after Heat ON is displayed and then check the registers. |
| fan when the furnace has warmed up to a setpoint. | 2. Check Heating and Cooling system. | |
| 2. Heating or cooling equipment is not operating. | ||
| Control does not respond to keypad presses. | 1. “Keypad locked” is displayed on LCD. | 1. Unlock keypad – press Up+Down arrow together until “Keypad locked” |
| 2. Keypad failure. | 2. Replace Control. | |
| Fan does not operate properly in heat or cool mode. | 1. Incorrect wiring. | 1. Correct wiring. |
| 2. Heating or cooling equipment inoperative. | 2. Repair system. | |
| Fan runs all the time. | 1. Fan mode set to ON. | 1. Set fan mode to AUTO. |
| 2. Shorted control wiring. | 2. Check / Repair wiring. | |
| Cooling cycle too fast or too slow. (Narrow or wide temperature swing). | The location of the control and/or the size of the cooling system may be influencing the cycle rate. | Verify cycle rate adjustment |
| Heating cycle too fast or too slow. (Narrow or wide temperature swing). | The location of the control and/or the size of the heating system may be influencing the cycle rate. | Verify cycle rate adjustment |
| Problem | Solution |
|---|---|
| Some or all keys on the display do not work; why? | Comfort control screen is locked |
| Comfort control is asking for heating or cooling to come on (screen shows “Heat On” or “Cool On” in display) but there is no heating or cooling running | Call your local heating and/or cooling contractor to check your heating and/or cooling system |
| Under the Fan on the screen, Auto and On or Auto and Circ are shown. What does this mean? | The Fan is programmed for either On or Circulate. |
| Why doesn’t the comfort control respond when I touch the keys? | Check to determine if the screen is in the Locked or Clean mode |
| Symptom | Possible Cause | Action |
|---|---|---|
| Display does not come on. | Comfort control is not being powered. | Check for 24 Vac between В 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 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 if the circuit breaker is tripped-reset the circuit breaker. | ||
| Check if the fuse is blown-replace the fuse. Check if the system switch is in the Off position-set to Heat or Cool. | ||
| Temperature settings will not change (Example: cannot set the heating higher or the cooling lower). | The upper or lower temperature limits were reached. | Check that the temperature setpoints are within range |
| Heating: 50° to 99° F (10° to 37° C) Cooling: 50° to 99° F (10° to 37° C). | ||
| Heating will not come on. | No power to the thermostat. | Check that the setpoint is above room temperature-reset temperature or wait for room temperature to fall. |
| System selection is not set to Heat. Heating setpoint is below room temperature. | Check if the circuit breaker is tripped-reset the circuit breaker. | |
| Check if the fuse is blown-replace the fuse. Check if the system switch at the equipment is in the Off position-set to Heat position. Wait five minutes for the system to respond. | ||
| Cooling will not come on. | No power to the thermostat. | Check that the setpoint is below room temperature-reset temperature or wait for room temperature to rise. |
| System selection is not set to Cool. Cooling setpoint is above room temperature. | Check if the circuit breaker is tripped-reset the circuit breaker. | |
| Check if the fuse is blown-replace the fuse. Check if the system switch at the equipment is in the Off position-set to Cool position. Wait five minutes for the system to respond. |
| 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. |