Heat is a form of energy that we all experience every day. That is because everything has some amount of heat. That is, everything has some amount of heat unless it reaches a temperature of absolute zero. Absolute zero is about minus 459 degrees F or minus 273 degrees C. At that low temperature, all movement at the molecular level stops and no heat is present. Everything else at temperatures above absolute zero has some amount of heat in it.

Knowing that everything has some heat, remember it is just that objects that feel cooler have less heat in them than objects that feel warmer. That is why automotive air conditioning is all about heat. The A/C system does not make cold air. It only removes the heat from the air.

The major sources of heat in our environment are from the Sun, Friction and Fire. In the case of the automobile A/C system, heat loads are generated by the sum, ambient air temperatures, the engine and transmission, which are developing heat because of friction, the road, the vehicle exhaust system and other passengers in the vehicle.