I never realized just how hot car engines can get while you’re driving peacefully down the road. Even when your temperature gauge is sitting safely at the middle point between hot and cold, the area underneath your car’s hood is still extremely hot. The air that is pushed into the engine as the car flies down the road is part of what cools these warm components. The primary source of engine cooling is the radiator. If the radiator leaks or naturally burns down its supply of coolant, then you run the risk of your engine overheating. As long as the radiator is maintained without damages, your car should stay at a safe operating heat at almost all times. Air conditioning systems, whether in commercial or residential applications, are much the same way. They have a transfer of energy from hot to cold—the refrigerant gets warm after energy is absorbed during the cooling cycle. The heat has to be released somewhere, which is why you see condensers sitting in yards instead of inside homes. If they weren’t outside, they would be warming the very space they’re trying to cool. This is the exact paradox you deal with if you buy a portable air conditioner. The warm compressor is inside the same enclosure as the cold evaporator coil, so the device has to draw some of the conditioned air back into the system to cool the warm components. This warm air is pushed outdoors through the exhaust hose. For this reason primarily, they’re not as energy efficient as window air conditioners. If you don’t have the right kind of window in your home, you might have no other choice but to use a portable air conditioning system.