Why Your Thermostat Is Blank – And How to Fix It
Have you ever woken up on a cold winter morning expecting your home to be toasty warm, only to find it’s not?
Yeah, me too.
You head downstairs and stare at your thermostat, wondering why it’s blank.
First, the good news. A misbehaving thermostat is typically way easier—and cheaper—to fix than a misbehaving furnace. Or air conditioner, for that matter.
Below, I’ll list several possible reasons why your thermostat is blank and how to fix the issue.
Here we go.
9 Reasons Why Your Thermostat is Blank
As you probably know, your thermostat is one of the most important parts of your HVAC system. I like to call it the hub.
With no thermostat, you can’t turn anything on or off—without flipping a breaker, that is—and you can’t set or adjust your indoor temps. It’s your command center!
So a blank screen on your thermostat is a bad thing, but as I mentioned above, it could be a simple thing too. Let’s consider possible scenarios and fixes.
1. Power Supply
If you have a blank screen, this is the first thing you should check. Like your computer, TV, smartphone, or anything else with a display, it needs a power source to light up.
Solution: Head to your home’s electrical panel. If you have everything labeled, this is an easy job. Just check to see if the breaker that controls your thermostat has tripped. If so, reset it. If they’re not labeled, you will need to test each breaker.
Without actually turning everything on and off, if you just gently test the switch, you can tell if it isn’t fully engaged.
2. Check Your Batteries
While your thermostat is wired to your HVAC system, the controls and display may be battery-powered. Dead or weak batteries can be the cause of a blank screen.
Solution: Check and replace batteries if necessary.
3. Low Voltage
While some thermostats power the display with batteries, others are powered via a 24-volt transformer. If the voltage has dropped, this can impact performance.
Solution 1: Check to see if you have a tripped circuit breaker. If you reset it and it immediately trips again, you’ll need to call an HVAC pro.
Solution 2: This could be a wiring issue or a bad transformer. Check the wires to the transformer for corrosion or pest interference. If you see any issues, you should call a pro.
4. Blown Fuse
If none of the other power issues have solved your problem, you may have a blown fuse.
Solution: Remove your thermostat and look for a fuse. It looks like a tiny, tube-like lightbulb with filaments in it. Just like you can tell if an incandescent light bulb has blown out by checking for a broken filament, you can follow the same procedure for a fuse.
If your fuse has blown, replace it.
5. Display Brightness
Ever tried seeing your smartphone display in full sunlight? If you don’t have it auto-adjusting, it may look like your screen is blank. The same can happen with some thermostat displays.
Solution. Check your manual to see if this is a feature offered with your thermostat. If it is, simply adjust your screen’s brightness level.
6. Open Furnace Door
Depending on the brand of thermostat you have, it may have an override that kicks in if the furnace door is open. Meaning they will shut themselves off.
Solution: Run down to the basement—or wherever your furnace is—and make sure the door is closed.
7. Dirty Air Filters
Have you been negligent when it comes to replacing filters? Many require a change every three months.
Over time, your filters can become so clogged with dirt they impede airflow. If that happens, your system can shut itself down.
Solution: Check to see if your air filter needs to be replaced and then get in the habit of replacing it regularly.
8. Incompatible Parts
It’s always best to buy and install both a furnace and an air conditioner at the same time, but that isn’t always possible or even practical.
The problem is, your HVAC needs to operate as a complete system. So if you’ve recently replaced a furnace, condenser coil (outside), or evaporator (inside), or another component, and one of them isn’t working properly with the rest of the system, it can cause issues with the entire system.
Solution: If you meet the above criteria—you’ve recently had something added or replaced—and now you have a blank thermostat or a system that isn’t turning on, you should call a pro.
9. It’s Time to Replace Your Thermostat
Nothing today is built to last indefinitely. Excuse my cynicism, but at some point, decades ago, manufacturers realized they’d make more money if things had shorter than forever life cycles.
So if your thermostat is reaching old age—about 10 years—none of the above may be the reason or help. You may just need to buy a new thermostat.
If your thermostat is more than10 years old, needing a new one isn’t necessarily a bad thing. There have been significant advances in their technology in the last decade. If you’re into creating a smart home, a wi-fi or smart thermostat may be an exciting purchase for you.
Not everyone lives on a set schedule that allows them to precisely program their home thermostat. Being able to communicate with your thermostat and adjust your HVAC from your smartphone or watch as you head home might be a huge bonus.
A smart thermostat can even learn the patterns of your household and adjust your heating and cooling accordingly. How cool is that?
Solution: Shop for a new thermostat.
How to Get the Most Out of Your Programmable Thermostat
Programmable thermostats are marketed as a great way to increase energy efficiency. But in themselves, they don’t do this. You could be just as energy efficient with your old-style mechanical thermostat, you’d just need to keep changing it manually.
Set a Schedule
Take the time to properly set up your thermostat. And consider your schedule before you do.
Then do the following:
- Program your thermostat to lower your temperature about an hour before you go to bed and raise it about half an hour before you get up
- If everyone is out of the house during the day at work and or school, use the HOLD function to keep the temperature at an energy-saving temperature
A word of warning on that second guideline.
Don’t raise or lower the HOLD temperature too severely because you don’t want huge fluctuations. So if you like the thermostat at 76 in the summer, adjust it to hold at 80. Or if you like it at 70 in the winter, hold it at 66.
This way you don’t cancel out any energy savings by overworking your system to bring it back to your desired temps.
And just like you raise and lower temps before you go to bed or get up, set your schedule so that by the time you leave or get home, your thermostat has reached your desired indoor temperature.
Now Leave it Alone
You’ve put a lot of time and thought into setting your schedule. Now don’t be tempted to override them.
Once you’ve set it up, leave it be. Constantly overriding your set temps can just lead to higher bills and an uncomfortable home.
Regularly Check Your Batteries
Unfortunately, not all thermostats give you a heads up when it’s time to replace the batteries. If yours is one of them, set up a schedule to replace them. Maybe every fall when you check your smoke detector batteries.
Clearly, there are a number of reasons why your thermostat might be blank.
You might just need to replace your batteries or make sure your furnace door is open. Or maybe something else.
- Power Supply
- Check Your Batteries
- Low Voltage
- Blown Fuse
- Display Brightness
- Open Furnace Door
- Dirty Air Filters
- Incompatible Parts
- It’s Time to Replace Your Thermostat
Hopefully, one of the solutions provided answers to why your thermostat is blank. Thanks for reading!
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