air conditioner compressor and condenser outside of brick home
air conditioner compressor and condenser outside of brick home

The air conditioner compressor and condenser are two parts of an air conditioner that are easily confused. Most people who own air conditioners can’t identify the air conditioner’s main components and don’t have a good understanding of how these appliances work. However, homeowners need to know how their appliances function to maintain them and identify issues when they occur. Maintenance and early detection of problems can help you avoid costly repairs. When repairs become necessary, knowing the air conditioner parts will help you understand what the repair involves. The air conditioning compressor and the condenser are two components to become familiar with because they are two essential parts of the entire air conditioning system.

The Basic Air Conditioning Process

There are four basic components of an air conditioning system:

  • Evaporator
  • Compressor
  • Condenser
  • Expansion valve

The evaporator, compressor, condenser, and expansion valve are four essential components of an air conditioner. The components are connected by refrigerant lines, forming a closed circuit. Refrigerant flows through the lines and cools the home by transferring heat from inside the home to the outside. As the refrigerant travels the circuit, it changes continuously from a cold liquid to a hot vapor or gas. The evaporator, compressor, condenser, and expansion valve assist heat transfer.

HVAC air conditioner refrigeration cycle diagram

First, the cold, liquid refrigerant absorbs heat inside the home when warm air passes over the evaporator coils. The cooled air is blown into the house through the vents. The refrigerant absorbs heat and changes its state to a warm vapor. Next, the refrigerant travels to the compressor. The compressor pressurizes and heats the refrigerant, a process necessary for the heat to be removed from the refrigerant subsequently. Then, the compressor pumps the refrigerant to the condenser. The refrigerant travels through the condenser coils, releasing the refrigerant’s heat outside. As a result, the refrigerant cools. Finally, the refrigerant travels to the expansion valve, which depressurizes the refrigerant and turns it into a cold liquid. The refrigerant is pumped back into the home to the evaporator coils, and the cycle is repeated.

What Is an Air Conditioning Compressor?

variable speed air conditioner compressor diagram

The air conditioning compressor is a vital component of the AC system, often referred to as the “heart” of the air conditioner. It pumps refrigerant through the air conditioning system to cool air inside the home. The compressor is located inside the central AC unit known as the condenser unit.

How an Air Conditioner Compressor Works

The compressor receives the refrigerant after it has absorbed the heat from the home’s air. At this point, the refrigerant is a warm, low-pressure vapor. The refrigerant will eventually circulate back inside the house to repeat the heat-removal cycle, but first, the refrigerant must be returned to a cold, liquid state. The compressor performs the initial step in the cooling process applying energy until the refrigerant becomes a hot, high-pressure vapor. Using heat and pressure on the refrigerant serves two purposes. One, the refrigerant must be heated to a temperature higher than the outside air to release its heat as it travels through the condenser’s coils. Two, the pressurization allows the refrigerant to flow smoothly through the coils. After the compressor heats and pressurizes the refrigerant, it flows to the condenser, and the heat is removed.

Types of Compressors

how a reciprocating air conditioner compressor works diagram

Reciprocating Air Conditioner Compressor

The reciprocating compressor is the most common type of compressor. It is versatile and very efficient. A motor and crankshaft move pistons up and down inside cylinders, creating a vacuum effect. Refrigerant vapor is sucked into the cylinders when the pistons move down and compressed when the pistons move up. The compressed vapor is then pushed into the condenser. A reciprocating compressor may contain up to eight pistons.

how scroll air conditioner compressor works diagram

Scroll Air Conditioning Compressor

The scroll compressor is the newest type of compressor and is gaining popularity for being more reliable and efficient than reciprocating compressors due to fewer moving parts. A coil, or scroll, resembling a spring is fixed in the center. Another scroll rotates around the fixed scroll, pushing refrigerant towards the center and compressing it. The refrigerant then moves to the condenser.

how a screw air conditioner compressor works diagram

Screw Air Conditioning Compressor

Screw compressors are used in large buildings with lots of air to cool and circulate. Screw compressors are reliable and efficient, but they would not be cost-effective in homes and small buildings. Two large helical rotors, or screws, rotate and push air from the compressor’s intake. As the space is reduced, the refrigerant is pushed through the compressor to the outtake and the condenser.

how rotary air conditioner compressor works diagram

Rotary Air Conditioning Compressor

Rotary compressors are reliable, small, quiet, and vibrate less than other compressors. They are often used in applications where noise is a consideration. The compressor contains a shaft with attached blades or vanes. The blades push refrigerant through the cylinder and as the shaft rotates, compressing the refrigerant. Then, the refrigerant flows to the condenser.

how a Centrifugal air conditioner compressor works diagram

Centrifugal Air Conditioning Compressor

A centrifugal compressor is the most extensive and most expensive type of compressor. Centrifugal compressors are used in large commercial HVAC systems. Refrigerant is sucked into the center of a spoked disk called an impeller. The impeller spins, and centrifugal force drives the refrigerant to the outside edge of the impeller, compressing it before it’s released into the condenser. Few moving parts make this compressor reliable and efficient.

What Is a Condenser in an Air Conditioner?

mini split air conditioner condenser coil illustration

An AC condenser releases heat that the refrigerant has removed from the home’s air. The condenser is the main unit located outside the home. It resembles a box encased in thin metal fins. The compressor removes heat from refrigerant vapor, turning the refrigerant back to a liquid as it cools.

How a Condenser works

After the compressor applies energy to the refrigerant, the hot, high-pressure refrigerant vapor is released into the condenser. The surface of the condenser is covered in coils, usually made of copper. The refrigerant moves through the coils while the condenser fan supplies cool air. The air cools the refrigerant in the coils, and the metal fins outside of the unit conduct the heat away and into the outside air. The refrigerant condenses as it cools, becoming a liquid. Finally, the refrigerant flows into the expansion valve, which reduces the refrigerant’s pressure, cooling it further. Once the refrigerant returns to a cold, liquid state, it can return to the evaporator coils to cool the home’s air.

Types of Condensers

air cooled air conditioner condenser diagram

Air-Cooled Condensers

Air-cooled condensers use circulating air to cool the refrigerant in the coils. Air is induced by a natural draft or supplied by a fan blowing across the coils. Air-cooled condensers are most commonly used in residential and small office air conditioners.

water-cooled air conditioner condenser diagram

Water-Cooled Condensers

Water-cooled condensers, also known as double-pipe condensers, use water to cool the refrigerant in the coils. Water circulates through tubes enclosed in a shell, while refrigerant circulates in another set of lines between the water tubes, hence the name double-pipe condenser. Water-cooled condensers are economical and eco-friendly; water does not have to be disposed of and is not wasted.

evaporative air conditioner condenser diagram

Combined Air and Water-cooled Condensers

Combined air and water-cooled condensers, also known as evaporative condensers, use air and water to cool refrigerant in the coils. Water is sprayed onto the coils from above, and a fan beneath the coils blows air across them. A cooling effect is created as the water evaporates from the coils. Any water that fails to evaporate is re-circulated.

Air Conditioner Compressor vs. Condenser Comparison Table

Compressor Condenser
Function
Reduces the volume of gas to add pressure
Takes in the pressurized gas turning it into a liquid-vapor
Types
ReciprocatingRotaryCentrifugalScrew and Scroll
Air-cooledWater-cooledEvaporative
Components
Electric motor, pump, and receiver
Main unit, coil, and fan
Order of Function
Works before the condenser
Works after the compressor
Location of Placement
Inside the main unit of the air conditioner
Outside the home/structure

What Do I Do if My Compressor or Condenser Stops Working?

Regular maintenance and scheduled air conditioner inspections are the keys to keeping your air conditioner running properly. If your A/C compressor doesn't turn on or your air conditioner is blowing warm air or stops working, call an HVAC technician to inspect the unit and perform any necessary repairs. Only a professional HVAC technician can replace the compressor and handle the refrigerant.

Air conditioning

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