If you get too hot at home, you probably head over to the thermostat and adjust the temperature. Within seconds, you’ll be greeted with the sound of your A/C turning on, and you know you’ll be cool again soon. Technology is amazing when it’s working properly, but when you’re staring at a blank thermostat, you’re probably less than thrilled.
If your thermostat is blank, it probably needs new batteries. If the batteries are dead, the thermostat won’t be able to function properly, so start by replacing them. If it’s not the batteries, the most likely cause is a tripped circuit breaker. Loose wiring or display settings could also cause the problem.
Importance of a Functioning Thermostat
Your thermostat is a critical part of your HVAC system. It’s where you control the temperature settings so the system knows when it should come and turn off. This small control panel is like the brain of your A/C system, so when it’s not working properly, you’ll want to address it as quickly as possible.
Thermostats have changed a lot over the years, and now most people have some sort of digital display on their home system. So when the display is blank, you’ll have a hard time setting your system or knowing what’s going on with it.
Your thermostat measures the ambient temperature inside your home. That way, when you tell the system you want the temperature to be at 74 degrees, it will be able to respond accordingly to maintain your desired temperature. Without the thermostat, your system won’t be able to keep your home and family comfortable.
This small, unassuming device is what regulates and monitors what’s going on with the climate conditions inside your home. No matter how well your A/C runs, if the thermostat isn’t on and functioning properly, the system won’t work correctly.
The thermostat is also where you can adjust your fan settings, switch the system from heating to cooling, and so on. So, keeping your thermostat in good working order is critical to maintaining comfortable temperatures inside your home all year long.
Reasons Your Thermostat May Be Blank
If your thermostat is blank, it doesn’t mean that your whole system is shot. The problem may be more common than you think, especially if you’ve recently experienced a power outage.
In most cases, a blank thermostat is due to a problem with the power source. Whether it’s dead batteries or an issue with the hardwired device, restoring power will often correct the issue. However, the problem could also be due to a tripped safety switch, blown fuse, or display settings.
Some simple troubleshooting may save you some money for a service call, so start with these first.
Troubleshooting a Blank Screen on Your Thermostat
Batteries Are Dead
Like with many other electronic devices, dead batteries are normally to blame when the thermostat has a blank display. Most thermostats take either standard AA batteries or a 3-volt lithium battery, but you’ll be able to check by removing the thermostat’s cover.
Often, digital thermostat displays will indicate when the battery is starting to get low. You may see a flashing signal to indicate weak battery strength, either a battery-shaped icon or the word “battery” on the screen.
Stay ahead of the problem by checking your batteries every 6-months to a year. If you replace the batteries with new ones, give it a moment to power up again to know if it fixed the problem.
Circuit Breaker is Tripped
If the problem isn’t the batteries, it could still be an issue with the thermostat’s power source. If you recently had a power outage or flicker, the breaker could be tripped. In fact, the breaker could trip for a number of reasons, so it never hurts to check.
Inside your circuit breaker box, there should be labels to indicate which breaker(s) are connected to your A/C system. Try flipping the breaker switch “off” then “on” and wait a moment. If the display comes back on, you’ll know you fixed the problem. However, if the breaker continues to trip, you could have an electrical problem that needs to be evaluated by a professional.
Safety Switch Triggered
Most A/C systems are equipped with safety features to keep people safe when the system malfunctions or has other issues. For some systems, a safety switch may shut the system down in the event that the drain lines are backing up (to prevent flooding) or because of issues with the electrical system.
If the safety switch is triggered, your thermostat may not work correctly. The switch will need to be reset to get it up and running again, so you may need to call a service technician to diagnose and correct the problem that tripped it in the first place.
Over time, your thermostat will suffer from wear and tear from normal use. Sometimes, the thermostat display may be blank because the unit is broken and needs replacing. Thermostats can last quite a while, sometimes 10-20 years. Still, you may need to replace yours if it’s old and worn out.
Physical damage or water damage can also short your thermostat. Or if the digital display is cracked or broken, you may not be able to fix the thermostat and could be forced to replace it instead.
Loose Connections or Bad Wiring
Behind the thermostat’s cover, you may be surprised to find a large number of wires. The A/C system is complex and uses electrical signals to know when it needs to turn on and off. If those wires get loose or the connection is bad, the thermostat may not function correctly.
Sometimes, wires can come loose over time due to vibrations and disruptions in the home. In other cases, pests (like rodents) can chew through wiring and cause problems. Many times, the issue can be traced back to a poor installation job.
Before you start poking around the wires, be sure to shut off the power to the thermostat. It’s always best to call a professional if you’re not experienced in working with electricity.
The furnace Door is Open
The furnace door should be closed while your HVAC system is running. If the door isn’t closed all the way, the system may not run. Some thermostats are particularly sensitive to this issue and won’t work at all if the furnace door is open.
Brands like Honeywell are known for this safety feature, so if you have a furnace, double-check that the door is firmly closed and sealed. You can also try opening the door and closing it again to see if that resolves the issue.
Low Display Brightness
Sometimes, the thermostat may not actually be blank. Instead, it could just be on a very dimly lit setting. Some digital displays have brightness features that auto-dim when there’s a lot of light shining on the screen. You can try shielding the screen with your hands to block out the light and see if that’s the issue. Otherwise, check for a brightness adjustment setting to see if you can change it manually.
Similar to a tripped circuit breaker, a blown fuse could cut the power to your thermostat and leave you with a blank display. If you’ve recently experienced a power loss or surge, you may have also blown a fuse. Check the fuse box to see if there is a blown fuse. If you find one, you can easily swap it out yourself. However, if it blows again, you should call a professional to check it out.
What if I Need to Replace My Thermostat?
If you don’t know what’s causing the problem with your thermostat, you may want to call a service technician to take a look, especially if you suspect an electrical problem. However, if the thermostat is old and worn out or you want to upgrade to a newer model, replacing it with a new one is a simple task.
You will need:
- Cordless Drill and Bits
- Wall Anchors
Once you have the materials, swapping the thermostat is as simple as removing the old one and replacing it with the new one. Be sure to take a picture of the wiring setup before you disconnect the old thermostat, and make sure you wire the new one the same way.
When your thermostat isn’t working properly, you’ll have trouble keeping your home at a comfortable temperature.
So you’ll definitely want to get it taken care of as soon as possible. Start with these simple troubleshooting steps, but if you’re still having an issue, be sure to call a professional sooner rather than later.
Ruben has a diverse background in the home services industry, with experience running a construction company, a kitchen and bath showroom, and a moving and relocation company. This breadth of experience has provided him with a wealth of knowledge and expertise in various areas of home improvement in general and specifically in the heating and plumbing niche.