An air conditioner takes warm air and makes it cooler by transferring the heat using evaporation principles. When you turn on your air conditioner, the thermostat control measures the air temperature. If the air temperature is warmer than the setting on the thermostat, it sends power to the compressor.
After the compressor gets power from the thermostat, it starts pumping and compresses a refrigerant gas, causing it to become a hot, high-pressure gas. Next, this hot gas flows through a set of condenser coils where it dissipates its heat to the surrounding air which is pushed past the coils by a fan, and then condenses into a liquid. Following that, the liquid flows through what’s called a capillary tube. During this process, the liquid refrigerant evaporates to become a cold, low-pressure gas. This cold gas flows through a set of evaporator coils which allows the gas to absorb heat, and by absorbing that heat; it cools down the air which passes over the coils, and then this cold air gets pushed into the room or building by the air conditioner’s fan. When warm, moist air goes over these coils, they collect condensation, which drips off and flows through a drain tube into a drip tray. This water usually flows to the back of the unit where it is sometimes thrown by the condenser coil fan onto the condenser coils to help cool the hot coils down. You may even hear the sound of the water getting splashed around. This part of the process also reduces the humidity levels in the room or house.
A fan blows the air from the room over the cold evaporator coils and back into the room at a cooler temperature to cool the room. It also blows warm outside air over the condensor coils so they don’t get too hot. The selector switch controls how fast the fan motor goes and therefore how much air is moved.
Once the thermostat measures the temperature of the room to be slightly lower than the control setting, it sends an electrical current which turns off the compressor. The fan may continue to blow the air between cooling cycles. Once the thermostat measures that the temperature is again above the desired temperature, the compressor shuts off until it gets the start signal, and the process begins again.