If your home has a programmable thermostat or a smart Wi-Fi thermostat, the screen on the thermostat should constantly be on even if your HVAC system is shut off. A blank screen can result if the thermostat has failed and needs replacing, but the problem can also result from numerous other issues. Some of these issues are things you can often fix on your own easily and don’t require any technical knowledge. If you do ever notice that your thermostat screen is blank, here are the steps you should take to help troubleshoot the problem.
Replace the Thermostat Batteries
Most all programmable and smart thermostats have batteries. On some units, the batteries are simply a backup and work to ensure that the thermostat settings don’t get reset whenever the power goes out. However, many thermostats use the batteries to power the screen. The batteries can sometimes become loose and prevent the screen from turning on. There is also a chance that the batteries are simply dead, which is why we would always recommend replacing the batteries as the first step any time your thermostat screen is blank.
Check the Brightness Setting
Many programmable thermostats have a setting that allows you to turn the screen brightness up and down. The brightness setting is always the next thing to check if your thermostat screen is blank, as there is always a chance that someone in your home accidentally turned the brightness down. The brightness can also get turned all the way down if the power goes out and the settings get reset. Some newer thermostats will also automatically adjust the brightness and turn it down to save power when the room is brightly lit.
When the screen brightness is turned all the way down, the screen can look like its blank if the room is too brightly lit. This is something you can check for by turning the lights off and checking to see if the screen is still blank. If the brightness setting is turned all the way down, you may only be able to read the screen when the room is dark and no light is shining on the screen. If the brightness setting is turned down, all you need to do is go into the settings and turn it back up until you can easily read the screen.
Make Sure the Circuit Breaker Isn’t Tripped
Your HVAC system is responsible for supplying power to the thermostat. Electricity flows from your main electrical panel to the HVAC system, and then a low-voltage wire runs from the system to the thermostat. If the circuit breaker that controls the HVAC system trips, the thermostat won’t have power and the screen may go blank. This is something you can easily check for on your own by opening the access door on your home’s main electrical panel. Each circuit in the panel should be clearly labeled so you should be able to immediately see if the HVAC circuit breaker is tripped.
If the breaker is tripped, resetting it should turn the screen on the thermostat back on. However, it is important that you don’t keep resetting the breaker if the system continuously causes it to trip. If the breaker constantly trips whenever your heating or AC tries to start, it typically means that the system has some sort of electrical issue. In this case, continually resetting the breaker could cause even more damage or potentially create a fire hazard. For this reason, it is always best to immediately contact an HVAC company and leave the system off if the breaker trips again after you’ve reset it.
Check the AC Drain Pan
All HVAC systems have different safety switches that are designed to shut off power to the system in the event of certain problems. If any of the safety switches trips, no power will flow to the thermostat and the screen may shut off. If your thermostat screen ever goes blank in the summer when your AC has been running, you should open the access door on your air handler compartment and check to see if the AC drain pan is full.
On most AC systems, the safety switch is located inside the drain pan. This switch is a float switch that will shut off power to the system and prevent it from running if there is ever too much water in the drain pan. This is important as the drain pan could start to overflow and lead to electrical issues or cause water damage. When the safety switch activates because the drain pan is too full, the thermostat and AC will automatically shut down and won’t turn on again until the pan has been emptied and the switch is reset.
There should never be any standing water in the drain pan as it will always flow out through the condensate drain lines and into either your sewer system or directly outside. A full drain pan indicates a clog somewhere in the drain system and that you need to have a technician clear the clog and then reset the safety switch.
Make Sure Your Furnace Door Is Closed
Some brands of thermostats are designed to automatically shut off as a safety precaution if the door on your furnace isn’t completely closed. This is especially the case with Honeywell thermostats, but some other models and brands may also have the same issue. This is another problem you can easily check for by opening the furnace door and then making sure to close it tightly. If your thermostat screen now comes back on, you can be sure that the door wasn’t fully closed.
Have a Technician Inspect Your Thermostat and HVAC System
If you have gone through all the above steps and your thermostat screen is still blank, it is time to call in professional help. A blank thermostat screen can be caused by a variety of different problems other than the ones we’ve already discussed, and the only way to determine the specific cause is to have a professional inspect the thermostat and the rest of your HVAC system. One possibility is that the thermostat is bad and needs to be replaced. The wiring that runs to the thermostat may also be damaged or loose, which means no electricity will flow to the thermostat.
Another possibility is that the high-temperature limit switch on your heating system was tripped. The limit switch will automatically shut off the furnace and the rest of the system if either the furnace itself or the blower ever overheats. The limit switch constantly measures the temperature of the furnace whenever it is running and will shut the furnace down and cut off the electricity to the system if the temperature ever rises above a set level.
If the limit switch ever trips, your thermostat and the rest of your heating system won’t work until everything cools down enough that the system can safely operate again. If the thermostat goes blank just after your furnace turns off and then starts working again after a few hours, you can be certain that the limit switch is the cause. In this case, you’ll still want to have the system inspected as overheating can cause serious damage and may also pose a major fire risk.
If you need help to troubleshoot a blank thermostat or any other HVAC issue, you can count on the team at BEST Air Conditioning Plumbing Repair. We specialize in all types of HVAC repairs as well as maintenance and installation, and we also offer a range of plumbing services for customers throughout the Las Vegas area. Contact us today if you need to schedule a service call or if you have any questions.