Your thermostat is what controls the heating and air conditioning systems in your home. If your thermostat isn’t working correctly, your HVAC system also won’t work. Thermostats can have a variety of issues that can prevent them from signaling the furnace or AC to turn on or make them only work intermittently. Your thermostat can also stop measuring the temperature accurately and may not signal the HVAC system to run when it should or it could signal it to turn off too soon. If your thermostat isn’t working or you suspect it has any issues, here are some steps you can take to troubleshoot the problem and hopefully determine what the specific issue is.
Check the Circuit Breaker
If the screen on your thermostat is suddenly blank, it indicates one of two things. It’s either that the thermostat has failed and needs to be replaced or that it isn’t receiving power for some reason. The first thing to do in this situation is open the door to your home’s main electrical panel and make sure the circuit breaker that your HVAC system is connected to isn’t tripped. All of the circuit breakers in an electrical panel are typically labeled so that you know what system or circuit each one corresponds to. If the breakers aren’t labeled but you see a 240-volt double breaker that is tripped, you can usually be fairly certain that that’s the breaker for your HVAC system.
If the breaker is tripped, you’ll want to reset it and then go back to the thermostat to check if it’s now working. If the breaker isn’t tripped or the thermostat screen is still blank, there could be a loose electrical connection or it may be that the wiring running between the thermostat and the HVAC control board is damaged. Your thermostat may also have simply failed due to age or a power surge could have burned it out. The only way to know for certain why your thermostat isn’t working is to have it inspected and tested by a certified HVAC technician.
Replace the Batteries
Before calling for an inspection, it’s also a good idea to replace the batteries in the thermostat. On most newer thermostats, the batteries are simply meant to provide backup power to ensure that the thermostat never resets and loses all of its settings when the power to your home goes out. However, some units use the batteries to power the screen so you should replace the batteries just to be sure.
Switch the Thermostat Setting
There are situations when the thermostat screen will show it is working, but your heating or air conditioning doesn’t come on when it should. This can happen due to an electrical issue or an issue with your furnace or air conditioner, but it could also be that the thermostat isn’t working or isn’t calibrated correctly. One thing you can do in this situation is to change the fan setting to “On.” If the fan comes on, you can at least be certain that the thermostat is still sending a signal to the HVAC system, so you can rule out any wiring issues with the unit.
You should then switch the thermostat to the opposite mode from what should be running, i.e., change it from cooling to heating or vice versa. You’ll then want to adjust the temperature setting to two to three degrees higher or lower than what the temperature on the thermostat reads so that your air conditioning or heating should come on. If your HVAC system won’t run in either mode, you’ll want to have it inspected. In this case, the problem could be related to the thermostat, the control board or an electrical issue.
If your heating or AC does come on when you switch the setting, you’ll then want to quickly shut it back off, and again, call for an inspection. In this case, you can at least be certain that the thermostat is properly calibrated and is signaling the HVAC system to run as it should. If the system only runs in one mode and not the other, the problem is definitely related to your furnace or AC.
Use a Thermometer To See If the Thermostat Is Calibrated Correctly
If your thermostat isn’t signaling your HVAC system to run when your home is hotter or colder than it should be, it’s a good idea to check that the thermostat is calibrated correctly and reading the right temperature. This is something you can easily do with any type of kitchen thermometer. You should tape the thermometer next to the thermostat at the exact same height. Before taping it to the wall, fold up a few pieces of paper towel and place this in between the thermometer and the wall. This step is important for ensuring that the thermometer is registering the actual air temperature and not the temperature of the wall.
Wait a few minutes and then check to see whether the thermometer registers the same temperature as the thermostat shows. If your thermostat is calibrated correctly, there should be no more than a two-to-three-degree difference between what temperature it shows and what the thermometer reads. If there is more of a difference in the two temperature readings, you’ll need to have a technician recalibrate the thermostat or possibly replace it if they determine the unit is wearing out.
Clean Any Dust From Inside the Thermostat
Thermostats can also malfunction if they get too dirty so this is also something you may want to check if your thermostat either isn’t signaling your HVAC system to run or isn’t showing the correct temperature. A dirty thermostat will often have issues where it can’t correctly read the temperature of the surrounding air as dust can essentially insulate it. As such, you may want to try and clean inside the unit if it isn’t registering the correct temperature.
Before cleaning the thermostat, you need to first shut off the circuit breaker so that it doesn’t have power. You can then take the cover off the thermostat and use either a soft-bristled brush or compressed air to gently clean away any dust and debris from inside the unit. You can then replace the cover and turn the power back on.
Check That the Thermostat Is Level
Most newer thermostats are electronic and have a digital sensor that reads the temperature, but some homes still have older mechanical thermostats that use a small vial of mercury to read the temperature. This type of mechanical thermostat has to be perfectly level to work correctly and register the correct temperature. Simply bumping a mechanical thermostat can make it not level and prevent it from working, so this is also something you should check if your unit contains mercury. If you have a level, place it on top of the thermostat to see if the air bubble is in between the two lines. You can often re-level a thermostat without needing to remove it by gently pushing on it until the level reads true.
Contact Healthy Home Heating & Cooling LLC for an Inspection
If you can’t determine why your thermostat isn’t working, our technicians are here to help. We can inspect your thermostat and its electrical connections and wiring to determine what the issue is and whether it can be repaired or if you need to replace the thermostat. Our team has years of experience with all types of HVAC repairs, and we can also assist if you need any air conditioning or heating maintenance or installation services. We serve customers throughout the De Pere area so give us a call today for all of your home’s heating and cooling needs.
