With spring now in full swing and summer just around the corner, you’ll soon be relying on your air conditioner for comfort. Understanding how your HVAC system works is key to keeping it running efficiently. At the core of your air conditioner’s ability to keep your house cool in hot weather are its essential components, particularly the air compressor.1 Here, we’ll explain precisely how an HVAC air compressor works and its vital role.
Main Components of an AC System
To truly grasp the function of an air compressor, it helps to understand the other main components of your air conditioning system:
- Evaporator (or Evaporator Coil): This is a vital part located in the indoor portion of your AC system.2 Its role is to absorb heat from your home’s air and transfer it to the refrigerant, which then carries this heat to another part of your air conditioner – the condenser.
- Condenser: This is the outdoor unit that you typically see next to your house.3 It contains coils and a fan, and its purpose is to release the heat captured from indoors to the outside air.4 The condenser then sends the now-cooled refrigerant back indoors through the evaporator to reduce your home’s temperature. The condenser works in close conjunction with the air compressor.
- HVAC Air Compressor: This is a mechanical device located inside the condenser unit (the outdoor portion of your HVAC system). The air compressor acts as the intermediary between the evaporator and the condenser.5 It is central to transferring heat from the indoors to the outdoors, ultimately providing cool air for your home.6 Air compressors are often referred to as the “heart” of an HVAC system because they drive the entire cooling cycle.7
- Expansion Valve: This is another crucial component, a small part fitted between the evaporator and condenser.8 It is essential for helping the refrigerant change from a high-pressure liquid to a low-pressure gas. The expansion valve also helps to cool the refrigerant, working seamlessly alongside the evaporator, condenser, and air compressor.9
These four components are all central to the cooling cycle.10 In this cycle, refrigerant is compressed and transformed into a hot, high-pressure gas before being cooled and turning into a low-pressure liquid, which then absorbs heat indoors and transitions back to a low-pressure gas to repeat the process.11
How Does an HVAC Air Compressor Work?
HVAC air compressors are fundamentally responsible for compressing or squeezing refrigerant gas and facilitating its transfer outside.12 Refrigerant is the working fluid used in air conditioners to cool air, and it has the unique ability to alternate from a low-pressure liquid to a high-pressure gas, absorbing and releasing heat in the process.13
As refrigerant travels through your HVAC system, it absorbs heat indoors and turns into a gas.14 This gaseous refrigerant then enters the air compressor.15 In turn, the air compressor squeezes this refrigerant gas into a smaller volume.16 During this process, the gas’s temperature and pressure significantly increase. Essentially, an air compressor transforms refrigerant from a low-pressure, cool gas into a high-pressure, hot gas. This heated and pressurised gas then gets shifted to the condenser, where it can release its absorbed heat to the outside air through a process called condensation.17 Thus, an air compressor works directly with the condenser to remove heat from your home.
The compressor also works within a continuous cycle. After releasing heat outdoors, the refrigerant cools and turns back into a liquid as it passes through the condenser and expansion valve.18 The compressor then draws this low-pressure liquid/gas mixture indoors to the evaporator, where it absorbs more heat and once again becomes a gas. The air compressor repeats this back-and-forth cycle, continuously circulating refrigerant to cool your home to the appropriate temperature setting.19 An air compressor is connected to your HVAC system through a network of piping that enables the seamless circulation of refrigerant between the evaporator, condenser, and itself.
However, if a compressor is not working properly, its ability to circulate and pressurise refrigerant is compromised. This can lead to insufficient airflow from your vents or, even worse, the circulation of warm air indoors. At the very least, a damaged compressor results in significantly lower energy efficiency, leading to higher bills, and should be promptly repaired or replaced.20
Types of HVAC Compressors
Several types of compressors are utilised in air conditioning systems, each suited to different applications:21
- Reciprocating Compressor: One of the most common types, particularly in residential AC systems and some lighter commercial settings.22 Reciprocating compressors operate similarly to a car engine, using a crankshaft that drives pistons located inside cylinders to compress the refrigerant gas.23 They are a popular choice for homes due to their efficiency.
- Rotary and Screw Compressors: These are two other types often found in residential HVAC systems, as well as some commercial applications.
- Rotary compressors rely on a revolving motion to compress refrigerant gas.24
- Screw compressors use two helical rotors (screws) that intermesh to compress or squeeze the gas.25Both types employ a rotational motion to reduce the volume of the gas and are used in various systems, including window units and central air conditioning.
- Rotary compressors rely on a revolving motion to compress refrigerant gas.24
- Centrifugal Compressors: These are mainly used in large-scale commercial air conditioning systems.26 This type of compressor increases pressure through a rapidly rotating impeller blade that moves circularly to compress the refrigerant gas.27 This option provides a very high cooling capacity and would be far too powerful for most residential homes.
Our experienced technicians can help you understand the specific type of compressor you have in your system and can expertly diagnose and repair it if necessary. Our team is also fully equipped to install new air compressors to resolve common air conditioning issues.
Air Conditioning and Compressor Issues
We understand that air conditioners can experience various issues, with problems related to the compressor being among the most critical. Our highly trained technicians are adept at evaluating your AC system, accurately determining the root cause of any issue, and getting your system working efficiently again quickly.28
Several key signs indicate that your air conditioner may need servicing due to a compressor problem:
- Warm air coming out of the vents is a primary indicator, suggesting the air compressor may have deteriorated and is no longer effectively compressing refrigerant to cool the air.29
- If you experience little or no AC airflow, this can also be a sign of a damaged air compressor struggling to circulate refrigerant.30
- Loud or strange noises coming from the outdoor condenser unit, such as banging, grinding, hissing, or screeching, are common indications of internal compressor malfunction.31
Other HVAC system problems that can impact or be caused by compressors include dirt accumulation on coils, which impedes the compressor’s operation and makes it work harder.32 You might also experience a refrigerant leak in your AC system, which can be caused by or lead to a faulty air compressor.33 If you are experiencing any of these signs, it is crucial that your system be evaluated by a professional HVAC technician without delay.
Most air compressors are designed to last about 10 to 15 years. If your unit has reached or exceeded this age, it may indeed be time to consider a new one. Likewise, if you’ve experienced frequent AC problems recently or if your energy bills have consistently increased without explanation, it could be a strong signal that your air conditioner’s efficiency has dropped, suggesting it’s time for a new unit. We can assist with comprehensive AC installations and ensure you get the right model for your home. Our expert technicians possess the knowledge and skills to install an entire air conditioning unit or replace critical parts like the air compressor, ensuring your home stays cool and comfortable this summer.
Reliable HVAC Services
For more information about air conditioning and other HVAC services, contact Black-Haak. As a family-owned and -operated heating, cooling, electrical, and plumbing company, we proudly provide services to Fox Valley, WI, and the surrounding areas. Since 1956, we have delivered reliable HVAC repairs, installation, and maintenance, building a legacy of trust and expertise.34
Call us today!