Your thermostat is obviously an essential part of your HVAC system. It signals your heating and air conditioning systems when to run and when to shut off. This means that if your thermostat isn’t working, your HVAC system also won’t work. There are a few different reasons why a thermostat display may stop functioning, and here are the things you should check for if you’re ever facing this situation.

1. Dead Batteries

Depending on the specific type and model of thermostat you have, it may be either hardwired directly into your electrical system or it might run off of battery power. If your thermostat does have batteries, the batteries could be what powers the display or they may simply be a backup so that the settings won’t get reset if the power ever goes out or a circuit breaker trips.

Unfortunately, this generally isn’t something that you can easily determine on your own. For this reason, the very first thing we would always recommend doing if your thermostat display isn’t working is to replace the batteries to see if this fixes the problem. If your thermostat doesn’t have batteries or it still doesn’t work after you’ve replaced them, then the issue is related to one of the other factors listed below.

2. Tripped Circuit Breaker

After checking your thermostat’s batteries, the next thing you will want to do is check your electrical panel to make sure that no circuit breakers are tripped. If your home has central heating, then your thermostat will usually be on the same circuit that powers your furnace and HVAC blower. If you only have central air conditioning, the thermostat and blower will typically be on one circuit and your outdoor AC unit will be on its own dedicated circuit.

In either case, there is a chance that the furnace or the blower had some issue that overloaded the circuit and caused the breaker to trip. If you do see that the breaker is tripped, try to reset it and see if your thermostat will now turn on.

3. Tripped Safety Switch

All central HVAC systems have safety switches that are designed to trigger and shut the system down should any issues arise that could lead to a safety hazard or potentially damage any of the system’s components. This can happen because the furnace or blower starts to overheat or sometimes even if the condensate drain pan for your AC gets too full. If the safety switch does trigger, the system’s transformer will no longer send power to your thermostat, and the display will shut off if the thermostat doesn’t have backup batteries.

The safety switch is usually located on the blower motor inside your air handler and can be reset by simply holding in the button for around 30 seconds. If you’re unsure of where your safety switch is or how to reset it, it is always easiest to have a technician check the switch for you and reset it if needed.

4. Loose or Damaged Wiring

Your thermostat display will also stop working if the wiring that runs between it and the furnace or blower is damaged or if any of the electrical connections are loose. The only way to know if this is the case is to have a professional inspect the wiring. The wiring can easily be damaged due to excess heat, and it can also simply start to degrade over time. We’ve also encountered numerous situations where a thermostat doesn’t work because mice have chewed through one of the wires.

5. Furnace Door Isn’t Fully Shut

Many modern furnaces are designed so that they can’t run if their door isn’t fully closed. Depending on the specific model, this issue can prevent the furnace from sending power to the thermostat so that its display won’t work. This is another issue that you can easily check on your own simply by opening the door on the front of the furnace and then closing it tightly.

6. Faulty Thermostat

There is also a chance that your thermostat isn’t working merely because it is faulty or broken. Even newer thermostats can suddenly have issues where they completely stop working and need to be replaced. A power surge has the potential to destroy a thermostat, or your thermostat may have simply reached the end of its life. This latter scenario is most likely if your thermostat is older than 10 years. This is typically about the maximum lifespan for most units.

If your thermostat isn’t working and you can’t figure out why, our technicians at Quality Cooling & Heating are ready to help. Our team specializes in all types of HVAC repairs as well as maintenance and new equipment installations, and we also offer a range of indoor air quality equipment and services. Give us a call today if you have any questions or need to schedule any HVAC service in the Austin or Abilene areas.

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