Your thermostat is a small but important device that controls the temperature in your home.
If your thermostat has gone blank or turns on momentarily before it turns off again, you may be concerned. Does it mean your furnace or air conditioning is broken? Not necessarily. Most of the time, a blank thermostat screen can be easily fixed if you can find out what caused it.
1. The Thermostat Batteries Died and Need to be Replaced
If your thermostat wall does not have a C-wire, or common wire, your thermostat most likely is not hooked up to your HVAC system for its power and needs batteries to operate. If your thermostat is blank, the first thing you should do is check the batteries. Chances are, the batteries have died and the thermostat simply can’t power on. Replace the batteries and see if your thermostat turns back on. Most thermostats display a low-battery symbol when the juice is running low.
2. Low Brightness Level
If your thermostat allows you to change the brightness level, check that the brightness isn’t turned down. Some thermostats will also automatically adjust their screen’s brightness level when there is too much light in the room to save battery power.
3. The Breaker Tripped
Most thermostats are connected to a home’s main electrical system. Sometimes, the thermostat or another electrical device can cause the breaker to trip or blow a fuse. This will shut off power to your thermostat and if there’s no battery backup, the screen will go blank. Check the breaker. If the breaker has tripped, simply flip the switch back to reset the circuit. If you have fuses, replace the fuse. Then check if this restores the thermostat screen.
4. The Safety Switch Tripped
Sometimes, an issue with your HVAC system can cause the transformer to stop sending voltage to run the thermostat. HVAC systems have built-in safety switches in the case of an unsafe situation. For your air conditioning system, start by checking the safety switch, which is installed in the drain pan. The safety switch works to detect hazardous problems like excess moisture or high temperatures within your system and prompts the entire system (thermostat included) to turn off before damages occur. If you notice that the sensor has gone off when you check the safety switch, contact an HVAC professional to inspect your AC. For your furnace, you will need to call in a professional for a diagnosis and repair.
5. Loose Wiring or Wiring Problems
Your thermostat has many electrical connections that serve various functions from the screen display to allow your thermostat to communicate with your HVAC system. If you recently had your thermostat installed or installed it yourself, the wires might not be firmly attached. If the thermostat is in a high-traffic room, the vibrations from people walking by can sometimes affect the wires. Additionally, rodents in attics might have chewed on the wires and caused issues. If you don’t have an electrical background, we don’t recommend attempting to fix loose connections or wiring problems yourself; leave it to the professionals!
6. The Furnace Door Is Open
Some thermostats, particularly Honeywell thermostats, are programmed to shut off entirely if a furnace door is open. Ensure your furnace door is closed securely and see if that fixes the problem.
7. The Thermostat Is Old or Broken
Though the average thermostat has a life expectancy of about 10 years, they do wear out. Therefore, if your thermostat has been around a while, has a blank screen, and isn’t working, it may be time for a replacement. If this is the problem, be sure to have a professional install the new one, as newer thermostats can be complicated and you don’t want to have issues in the future.
If you need HVAC or thermostat repair, or if you would like your system inspected, turn to St. Louis’ trusted professionals at Design Aire! The knowledgeable technicians of our HVAC company in St. Louis can take care of you and your family’s service needs.