What is an HVAC Compressor?

Presidential Heating & Air Conditioning

Gaithersburg HVAC Contractors


Share on Facebook


Tweet this


Share on LinkedIn0 shares on LinkedIn

an HVAC compressor on the side of a homeIf you are thinking about repairing or replacing your current HVAC system, you will want to know how it works. That functionality has a lot to do with the HVAC compressor within the system. If you are unsure what an HVAC compressor is or what it does for your system, you will likely want to understand it a bit better before getting your system serviced or replaced.

It is important to have a properly functioning HVAC compressor if you want to keep your home cool in the hot summer months. Without a properly working compressor, your system is virtually useless. Here, we will go over what an HVAC compressor is, how it works, and what it does to keep your home cool. Then, we will take a look at how to keep it maintained properly, along with finding a professional to properly service your system.

The Purpose of an HVAC Compressor

So, what exactly is an HVAC compressor? It is considered to be the heart of your HVAC system and is how your air conditioner is able to keep your home cool. One thing to remember is that air conditioners do not actually add coolness to a room. Rather, they remove heat from it. Coolness is what is left behind once the heat has been removed and brought outdoors by the system.

The compressor in your system is what pumps refrigerant throughout, removing the hot air from inside your home. That hot air is removed until the inside of your home has reached your desired temperature.

HVAC Compressor Functions

An HVAC compressor does exactly what its name suggests. It basically just compresses the refrigerant in the system in order to get it to the correct pressure and temperature. It does this before it moves the refrigerant through the condenser coil. It also circulates the refrigerant needed for heat exchange through the coils of the outdoor and indoor unit and applies energy to the refrigerant.

commercial HVAC compressors helping to cool a buildingThe cooling cycle begins when the compressor squeezes or compresses the refrigerant, which increases the temperature. That increased temperature exceeds that of the atmosphere surrounding it. That action of squeezing also pressurizes the refrigerant so that it transforms into a liquid form, allowing it to move freely through the system. The hot liquid form of the refrigerant moves to the condenser coil where it releases the excess heat. The fan blows air over the condenser coil to help with the release of the heat.

Failure of an HVAC Compressor

If the HVAC compressor fails, it will be impossible to get your home to a comfortable temperature. Without it, you cannot pump refrigerant through the system to reach your desired temperature. In many cases, you might need to consider replacing your HVAC compressor, or the full unit. Sometimes it is more cost-effective to replace the full system than just the compressor. Speaking with a professional will help you better understand which option is best for you.

Types of HVAC Compressors

There are a few different types of HVAC compressors available, but two are used most commonly.

Scroll Compressor

A scroll HVAC compressor uses a scroll that orbits a motor-driven crankshaft. It sucks in the refrigerant that is in vapor form and pushes it into a stationary scroll. The volume of that stationary scroll decreases so that the refrigerant compresses.

Piston Compressor

A piston HVAC compressor makes use of pistons, which are attached to a motor-driven crankshaft. Those pistons draw in the refrigerant and compresses it.

Where is the HVAC Compressor Located?

Most HVAC compressors look like black boxes that have lines running from and to them. In a split air conditioning system, which is the most common type found in homes, the compressor is in the unit that sits outside, usually to the side of the house. It is paired with the indoor unit, connected by tubing.

The outdoor unit of the HVAC system includes the HVAC compressor, condenser coil and fan. The refrigerant filled tubing runs from the internal unit to the external one.

Forms of Compressor Construction

two different types of HVAC compressorsThere are three different forms of compressor construction, which all have different functions.

Hermetically Sealed

Units that are hermetically-sealed have their compressor and motor sealed inside a steel casing that has been welded. While they cannot leak, they also cannot be reached for repairs.


Units that are semi-hermetic have their compressor and motor inside a steel shell, half of which is sealed shut with bolts and a gasket. These units can be accessed for repairs but also have the potential to leak.


Finally, there are open compressors. These have a compressor and motor as two separate units that are linked by coupling. This kind of HVAC compressor construction is typically only found in very big HVAC systems.

HVAC System Maintenance

The HVAC compressor in your system can be under a lot of stress during the hot summer months when it is working harder than usual. It essentially wears down over time, in much the same way a motor wears down. It will also be impacted by any dust and grime that builds up. Ultimately, the result is that the cooling cycle will no longer be functional, and the compressor will need to be replaced. Likewise, if there is a malfunction within the motor of the compressor, it will also cease to cool the home. If your HVAC compressor needs to be replaced, you may want to consider replacing the full system.

There are other potential issues with an HVAC compressor as well. It can develop a leak at the connectors, which would cause it to lose refrigerant. If there is a drop in the charge of the refrigerant, it can cause the compressor to be damaged.

Contact An HVAC Professional

If you suspect your HVAC compressor has an issue, or you are considering replacing the system altogether, reach out to Presidential Heating & Air Conditioning. In business since 1982, Presidential Heating & Air Conditioning can offer maintenance on your system, repair and replacement, or can simply answer any more questions you have on your particular HVAC compressor and system.

Related Posts
  • Getting Ready for Cooler Days – Fall HVAC Maintenance Guide Read More
  • How to Choose an Environmentally Friendly HVAC Contractor Read More
  • Energy Efficiency Tips: How To Save Money on Cooling Bills This Summer Read More