Parts of an AC Unit and What They Do

Air conditioner (AC) units monitor and regulate air temperature inside your home, but have you ever wondered how? Although an AC is a comprehensive system of components, it’s not too complex. We’ll break down the major components for you.

Evaporator Coils

Evaporator coils are used to deliver cool air into your home during hot summer months. The process by which air is cooled by the evaporator coils is as follows:

  • Air from inside your home is forced over the evaporator coils
  • Since heat flows naturally from hot to cold, the heat from the air inside your home is absorbed by the refrigerant inside the coils
  • The refrigerant changes state from liquid to vapor or gas
  • Cooler air is forced back into your home

The efficiency of the evaporator coil relies on how much refrigerant is available. Too little refrigerant results in operation failure. When too much refrigerant is available, it results in a parched evaporator and causes more liquid to transfer into the compressor.

Compressors

In order for heat to transfer back to the outdoors, the temperature of the refrigerant must be higher than the outdoor temperature. The main purpose of the compressor is to pressurize the refrigerant gas or vapor, thereby bringing it back to its liquid form. In order to disperse heat from the system, the air outside your home then cools the refrigerant.

The compressor runs on a motor and is therefore susceptible to mechanical problems if not properly maintained. It can stutter, overheat, and eventually burn out. If there are unusual sounds coming from the compressor, or if the AC isn’t keeping your home as cool as you’re used to, it could be because of a failed compressor.

Condenser Coils

A condenser coil is the opposite of an evaporator coil, as it contains hot liquid for heat transfer. Located outside of your home, it receives the high pressure, high-temperature refrigerant from the compressor.

The refrigerant inside the condenser coil releases heat energy with the aid of the condenser fan, which blows air over the coils. As the heat energy leaves the refrigerant, the cooler liquid then flows to the expansion valve.

Since the condenser coil is located outside of your home, it’s important to keep it clear of falling leaves, branches, or other debris. Ignoring regular maintenance could result in poor AC performance or electrical failure.

Expansion Valves

Located between the condenser coil and evaporator coil, the expansion valve removes the pressure from the condensed liquid refrigerant. As the pressure is removed, the temperature is decreased and the refrigerant changes from a liquid to a vapor form.

Keeping your expansion valve in good working order will ensure that your system stays efficient. A faulty expansion valve can result in your AC blowing warm air or frost, or it may keep your compressor working too hard.

Refrigerant

Refrigerant is a special fluid that changes states from liquid to vapor at convenient temperatures for the AC cycle. As it moves through the AC’s cooling tubes and copper coils, it absorbs heat from the inside of your home and transfers the heat energy outside.

One of the most common problems that can happen in the AC system is leaking refrigerant. Signs that refrigerant is leaking include:

  • Water puddles form around the compressor, evaporator coils, or condenser coils
  • Lower than usual airflow from the vents
  • The air inside your home feels warmer
  • It takes longer to cool down the house

If you notice any of these signs, it’s important to call a certified AC technician. At Briggs HVAC, we can fix small problems caused by leaking refrigerant in order to save your AC system from much bigger problems down the road.

Putting it All Together

The return vents inside your home force hot air into the AC system. As the hot air flows over the evaporator coils, the cold refrigerant absorbs the heat energy from the air.

After moving through the evaporator coil, the refrigerant discharges to the compressor. By pressurizing the refrigerant, the vapor inside the compressor is heated up even further. The hot vapor then flows through the condenser coils to facilitate heat transfer to the outdoors.

The refrigerant then cycles back over the expansion valve, depressurizing and cooling down. The AC system then performs the same heat absorption process over and over again.

Briggs HVAC: The Heating and Cooling Company

For professional residential HVAC sales and repair, contact us today. We service, maintain, and install heating and cooling systems to keep your home comfortable all year long.

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