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Beat the Heat: Your Ultimate Guide to Air Conditioning Pt. 3

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As the hotter months creep up, we rely on air conditioning systems to keep our homes and offices cool and comfortable. But are you aware of how these systems work? Air conditioning systems are complex machines, but understanding their basic principles can help you appreciate their efficiency and effectiveness. 

In the final part of this series, we’ll dive into the inner workings of air conditioning systems and explain how they manage to cool down your living spaces, even during the hottest days of summer.

The Basic Principles of Air Conditioning

At the heart of any air conditioning system are three essential components: the evaporator, the compressor, and the condenser. Together, these components achieve a simple objective: transfer heat from inside your home to the outdoor environment. 

To do this, air conditioners rely on a special substance called refrigerant, which circulates throughout the system and undergoes phase changes (from liquid to gas and vice versa) to absorb and release heat.

The Evaporator

The evaporator is the first component in the air conditioning process. It is inside your home, typically within the air handling unit connected to your ductwork. The evaporator is responsible for absorbing heat from your indoor air and transferring it to the refrigerant.

As the warm air from your home passes over the evaporator coils, the refrigerant inside these coils absorbs the heat energy. This causes the refrigerant to evaporate, changing from a cold liquid to a warmer gas. 

This process removes heat energy from your indoor space and helps lower humidity levels, as the cold evaporator coils cause moisture in the air to condense and be drained away.

The Compressor

Once the refrigerant has absorbed heat from your home and transformed it into a gas, it moves on to the compressor, typically located outside your home as part of the outdoor unit. The compressor’s primary function is to increase the pressure and temperature of the refrigerant gas.

By compressing the gas, the compressor effectively concentrates the heat energy within the refrigerant, preparing it for the next step in the process: the condenser.

The Condenser

The condenser is the final component in the air conditioning process and is also in the outdoor unit. The purpose of the condenser is to release the heat energy absorbed by the refrigerant back into the outdoor environment.

As the high-pressure, high-temperature refrigerant gas flows through the condenser coils, a fan blows outdoor air over the coils, helping to cool the refrigerant and release the heat energy. During this process, the refrigerant condenses back into a cool liquid, ready to be returned to the evaporator to start the cycle again.

The Expansion Valve

Before the chilly fluid coolant re-enters the evaporator, it goes through a regulating device called an expansion valve. 

This valve controls the refrigerant flow and lowers its pressure. Due to this decrease in pressure, the coolant can revert to a cold, low-pressure condition, prepared to take in additional heat from your home’s indoor air.

Thermostat and Controls

A thermostat manages your air conditioning system, enabling you to establish the preferred indoor temperature. If the inside temperature exceeds the chosen level, the thermostat communicates with the air conditioning system to initiate cooling. 

When the target temperature is attained, the thermostat instructs the system to cease cooling, saving energy and ensuring a pleasant indoor atmosphere.


Understanding the basic principles and components of air conditioning systems can help you appreciate the complex process responsible for keeping your home cool and comfortable during the hot summer months.

By working together, the evaporator, compressor, condenser, expansion valve, and thermostat create a continuous heat transfer cycle, ensuring your indoor spaces remain cool and your Canadian summer remains enjoyable.

Now that you’re familiar with the inner workings of your air conditioning system, you can confidently embark on the summer season with a renewed appreciation for the marvel of modern cooling technology.

If you’re looking for AC maintenance in Mississauga, we can help you. Furnace Home King Services is a heating and cooling company that puts its customers first! With over 43 years of experience, you can count on us to recommend the best for your space. Start today by getting a quote online!