If the screen of your thermostat has gone blank and your heating and cooling system doesn’t seem to be working properly, it could be a simple case of needing to change the batteries. Many people don’t realize their thermostat even uses batteries until they encounter a problem with it not working properly. Some assume there is a bigger issue and call a technician to diagnose their system, wasting precious time and money on a problem that can easily be resolved. By changing your thermostat batteries once every year, you can prevent this from occurring.