How the air conditioner works


It is summer time once again. Aside from making sure that our cars don’t overheat during our travels, we also make an effort to keep cool inside our rides. We do this by making sure that the air conditioning system in our car is working properly.

Something similar to the cooling system of the engine, the heat generated inside the cylinders is absorbed by the water surrounding it. The heated water is then pumped to the radiator where the heat from the water is absorbed by the thin tubes running along the core of the radiator. The tubes transfers the heat to the fins surrounding it and then transfers the heat to air.

An Air Conditioning system works basically on the same principle. Instead of using water, you use a refrigerant. A refrigerant is a compound that is used as the medium of heat transfer in a refrigeration system. It absorbs heat by evaporating and gives off heat by condensation.

In an A/C system, you have your compressor. This is used to circulate the refrigerant around the system. The compressor is driven by a belt–connected to the crankshaft. From the compressor you have your expansion valve. This valve controls the amount of refrigerant going to the evaporator—from a liquid state, to a vapor state. Now, the evaporator is located inside the cabin of the car. As the refrigerant in a vapor state passes through the evaporator, it absorbs the heat from the air. As the air looses its heat, it then becomes cold. A blower is used to circulate air around the cabin and through the evaporator. The refrigerant leaves the evaporator and heads to the receiver-drier. The purpose of the receiver-drier is to remove moisture from the refrigerant, trap contaminants, store excess refrigerant and ensures that only liquid refrigerant enters the expansion valve. After the receiver-drier, it enters the condenser. It is located outside of the car usually in front of the radiator. The refrigerant gives off the heat it absorbed from the evaporator while passing through the condenser. Just like a radiator. A fan helps air pass through the condenser to help dissipate the heat. From here it goes back into the compressor and the cycle begins again. As this happens the temperature inside the cabin will slowly get cooler. To how cold you want it to be will depend on the setting of the thermostat. Once you set the desired temperature, the thermostat will send a signal to stop the compressor. If the thermostat senses the cabin getting hotter, it will signal the compressor to start and it will bring down the temperature back to the desired setting.

As I mentioned the last time, a good A/C would need a good cooling system. That’s because the condenser is located in front of the radiator. If there is excess heat coming from the radiator, it can affect the condenser. The cooling fans of both the radiator and the condenser should always be working properly. Even the A/C compressor can be affected the excess heat. It is located in front of the engine, just behind the radiator.


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