If you're having problems with your facility's heating or cooling equipment, the first thing to check should be the thermostat. These devices control HVAC system operation and, if they fail, can make it look like there is something wrong with your heating or cooling equipment. Since thermostats are easily accessible and relatively inexpensive to replace, they should be among the first things to check if you have HVAC trouble. Keep the following tips in mind to determine if you need a thermostat replacement.