To test a heating and cooling thermostat, unscrew the unit and check the interior wiring. Most electronic thermostats can be taken apart with a screwdriver.
Ensure the power is turned off, and then use the appropriate screwdriver to disassemble the face plate. Two wires should be visible underneath the panel. These wires run into the electrical system behind the wall, so ensure that they are stabilized to prevent them from retracting. Remove these two wires from the terminals on the face plate. If there are more than two wires, only remove the red and white pieces.
Turn the furnace power back on, and check for ignition. If the burner ignites and the blower turns on, the electric thermostat is not reading the activity. In this instance, it is necessary to purchase and install a new electric thermostat. Staples carries electric thermostat plates and replacement parts. If the burner does not ignite, check the wires leading to the furnace. Additionally, tighten all screws and wiring to ensure everything is connected property. When assessing the state of the wiring within the wall, it may be necessary to hire a contractor to reach some of the areas. After testing, reconnect all wires, and assemble the face plate.