Home air-conditioning systems seem way too complicated to understand. Furnaces are much easier to understand for most of us – they heat up the air and filter it into your home through your ductwork. Your boilers create steam and hot water and then they relocate it around your house via pipes. But how in the world do air-conditioning systems create dehumidified, cool air when the outside temperature is high? In order to fully understand your air-conditioning system, you must go back to some basic principles your learned about in your school physics courses: the scientific law that as gas continues to cool, it slowly expands in volume.
What are the main components of an air-conditioning system?
There are 5 main components that go into any air-conditioning system and they must all work properly in order to have a fully-functioning air-conditioning unit.
We often refer to the refrigerant as the “blood” of the system, which is pumped through tubes within the air-conditioning unit. While it is moving through these specialized tubes, the refrigerant changes from a gas vapor to a liquid due to the heat it collects from your house, and then it ejects that heat outdoors. Refrigerant has a very low boiling point, which means that it changes from liquid to vapor at low temperatures. This refrigerant is moved around the air-conditioning system via a compressor.
Since we refer to the refrigerant as “blood”, we can therefore, think of the compressor as the “heart” of the system. It continuously pumps the refrigerant through a large copper loop. This allows the refrigerant to enter into the compressor (or heart) as a warm, low-pressure vapor, and leave as a hot, high-pressure vapor.
Now that the refrigerant is a hot, high-pressure vapor, via the compressor, it moves into the condenser, which is then cooled down. Condenser coils have small metal fins on them that draw heat from the coils. The condenser fan blows air on the fins, which helps the vapor cool down. Due to this cooling, the refrigerant is converted into a hot liquid, and then moves into the expansion valve.
The Expansion Valve
Now we get to the main way the refrigerant is cooled; the expansion valve. Now that the refrigerant is a hot liquid, it passes through the valve at very high pressure, and then comes out as a cool mist. This is able to happen due to the fact that, as the gas continues to expand, it naturally cools down.
The Evaporator Coil
The final part of the air-conditioning unit cycle happens in the evaporator coil. Low-pressure liquid is now led to the evaporator coil, which is located in your furnace. This is where the warmer air inside blows onto the evaporator coil and begins to heat it up. At the same time that this heating is occurring, the coil, which is carrying the cool gas, is blown across the evaporator. The refrigerant vapor moves back to the compressor and the outdoor condensing unit, and then expands. It cools one more time, and this continues the cooling cycle.