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Air Conditioning & Heating, Serving Northwest Houston

The Anatomy of a Home AC System

anatomy of a home AC system

After replacing hundreds of AC units in the Houston area, we have noticed that a lot of homeowners really don’t understand the anatomy of their home AC system. It is a good idea to have some understanding of the different parts of your AC unit and system, that way you as the homeowner can stay vigilant for any issues that may arise. Here is the anatomy of a home AC system.

Parts of Your AC Systems


What it is: The thermostat is the AC system’s control panel. It’s usually mounted on a wall inside your home and is where you set your desired temperature.

What it does: The thermostat measures the ambient room temperature and communicates with the AC system. When the room’s temperature rises above the setpoint, the thermostat signals the AC to turn on. Conversely, when the set temperature is achieved, the thermostat turns the AC off.

Evaporator Coil

What it is: Located inside the indoor unit or air handler, the evaporator coil is a series of tubes filled with refrigerant.

What it does: As warm indoor air passes over the evaporator coil, the refrigerant inside the coil absorbs the heat, causing the refrigerant to evaporate into a gas. This process cools the air that is then circulated back into your home.


What it is: The blower is a fan located inside the air handler or furnace.

What it does: It circulates air across the evaporator coil and then distributes the cooled air throughout your home via ductwork.

Condenser Coil

What it is: This coil is found in the outdoor unit and resembles the evaporator coil.

What it does: After the refrigerant has absorbed heat from inside your home and turned into a gas, it moves to the condenser coil. Here, the gas is condensed back into a liquid, releasing the heat it had absorbed earlier into the outdoor environment.


What it is: Also located in the outdoor unit, the compressor is often described as the heart of the AC system.

What it does: The compressor’s primary job is to compress the gaseous refrigerant from the evaporator coil, raising its temperature and pressure. This high-pressure, high-temperature gas is then sent to the condenser coil to release its heat.


What it is: A fan located in the outdoor unit, near the condenser coil.

What it does: As the refrigerant releases its heat in the condenser coil, the fan blows this heat away from the outdoor unit, assisting in the cooling process.


What it is: Usually found inside the indoor unit or return air duct, the filter is a mesh or fibrous screen.

What it does: The filter traps dust, pollen, pet dander, and other airborne particles, preventing them from recirculating in your home and clogging the AC components. This not only maintains air quality but also ensures the AC system runs efficiently.

Expansion Valve

What it is: Located between the condenser coil and the evaporator coil.

What it does: The expansion valve regulates the flow of refrigerant into the evaporator coil. It reduces the pressure and temperature of the refrigerant, allowing it to expand and cool before entering the evaporator coil.


What it is: A series of tubes or channels running through your home.

What it does: Ducts distribute the cooled (or heated) air throughout your home. They are crucial for ensuring even cooling or heating in every room.

Drainage System and Pan

What it is: Found beneath the evaporator coil, this system includes a pan and a drain.

What it does: As the AC cools your home, it also dehumidifies the air. The moisture it removes condenses on the evaporator coil and drips down into the pan, which is then drained away. This system prevents water damage and mold growth.


Your air conditioning unit is a symphony of parts working in tandem to provide comfort and maintain indoor air quality. Like any complex machine, each component has its unique role, and all parts must be in good working order for the system to operate efficiently.

Regular maintenance ensures each part of your AC system functions optimally, prolonging its life and maintaining its efficiency. Whether it’s cleaning or replacing a filter, checking the refrigerant levels, or ensuring the compressor is in top condition, an understanding of these parts empowers homeowners to make informed decisions about their AC system’s care.

Always trust a reputable HVAC professional for any repairs, maintenance, or queries about your AC unit. The team at Be Cool AC and Heating is always here to help Houston residents stay cool and informed!

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The Anatomy of a Home AC System

After replacing hundreds of AC units in the Houston area, we have noticed that a lot of homeowners really don’t understand the anatomy of their

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