How to Tell if Your Thermostat is Bad


Your thermostat is a critical component of your HVAC system as it regulates the temperature in your home. If it’s not working correctly, it can result in either a home that’s too hot or too cold, making it uncomfortable and expensive to maintain. Here are some signs that your thermostat may be broken and need replacement.

African American woman looking at thermostat

Inconsistent Temperature

When a thermostat is working correctly, it displays an accurate temperature of your indoor air. If the room feels much hotter or colder than the display temperature, your thermostat isn’t  accurately measuring temperature. If your home is too hot or too cold even though you have set the thermostat to a specific temperature, it could be a sign that the thermostat is not functioning correctly. Not only is this annoying and uncomfortable, but it can also be costly to try to manually regulate your home’s temperature.

No Response to Changes

If you change the temperature on your thermostat and it doesn’t seem to make a difference, it may indicate that the thermostat is no longer communicating with your HVAC system. A functional thermostat responds almost immediately when you adjust the temperature setting, and you can usually hear a quiet clicking sound followed by air circulating through the ductwork. You can also place your hand on the vent to feel for hot or cold air. If you don’t hear or feel anything within a minute or two of making the changes, your thermostat probably needs to be replaced.

Display Issues

If the screen on the face of your thermostat is dead, you can bet you’re dealing with a thermostat problem. Typically, the thermostat screen displays the room’s temperature and additional details about your programmed schedule. If the screen is dark, it’s likely due to dead batteries or a faulty thermostat.

No Heating or Cooling

A malfunctioning thermostat can prevent your heater or air conditioner from powering on, indicating the wiring has likely failed. Properly functioning electrical wires transmit messages between your thermostat and HVAC unit, communicating directions like when to circulate hot or cold air and what temperature is set. When these wires fail, the communication between the thermostat and HVAC is cut off, and the entire system stops functioning.

Heating or Cooling Won’t Stop

A faulty thermostat can also cause your HVAC to run non-stop. If you notice your system has been running for a long time without pause, try flipping the switch on the thermostat from “on” to “off.” If the system continues running while in the “off” position, it probably has faulty wiring or isn’t calibrated correctly.

Short Cycling

Short cycling is the HVAC term for warming or cooling cycles that are shorter than they should be, preventing your system from reaching the set temperature. When heating and cooling cycles are shortened, it puts extra stress on the compressor and can damage the entire HVAC system. If you notice your HVAC short cycling, the first and easiest thing to do is check your thermostat to see if it’s operating correctly.

Thermostat Not Following Programmed Settings

Programmable and smart thermostats should adhere to the settings and schedule you’ve set for your home. If you notice that your system is not sticking to the programmed settings, it could be a failing thermostat that requires a replacement.

Thermostat Repair, Replacement, and Installation

A functioning thermostat is essential for maintaining a comfortable and efficient home. If you suspect that your thermostat is broken, it’s essential to address the issue promptly to avoid further problems and potential damage. Call the HVAC pros at Chancey & Reynolds to diagnose the problem and determine the best course of action. Sometimes, a simple fix like cleaning the thermostat or replacing the batteries can solve the issue. In other instances, the best plan of action is installing a new thermostat

Your Partner in Heating and Cooling

Chancey & Reynolds has been installing, maintaining, and repairing HVAC systems in greater Knoxville since 1978. Our NATE-certified technicians determine precisely what your heating unit needs to ensure optimal performance. HVAC users across Knoxville and Lenoir City trust our team of specialists to keep their homes comfortable all year long. Contact us today to get started!