The APCET is a temperature controller that can be used as a cooling OR a heating controller. Once the APCET is connected to a power source, and the cooling or heating device is connected to the APCET's power outlet, the device connected will be automatically controlled by the settings on the APCET. The user can choose to have different day and night temperature settings which will be automatically switched to the correct mode by the built-in photocell. The knobs make it easy to adjust the settings and provide a quick visual verification of the current set points. The LEDs on the front of the unit will turn on and off to show the user the APCET's current operating status.