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AC Compressors (Everything You Need to Know)


An AC compressor is the heart of your air conditioning system.

It compresses the refrigerant, facilitating your home’s cooling (and heating if you have a heat pump).

Unfortunately, your AC compressor can get damaged if your system is old or if your HVAC system is not maintained correctly.

This guide will talk about what is an AC compressor, why an ac compressor may fail, the different types of AC compressors, how they work, and what it costs to replace one.

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What is an AC compressor?

The AC compressor is located on the outdoor unit, otherwise known as your unit’s condenser.

The compressor does what it’s named to do, “compress” the refrigerant in your HVAC system.

Your HVAC system utilizes a few basic concepts to cool or heat (if you have a heat pump) your home.

In short, it utilizes refrigeration and pressure changes to heat or cool your home.

You can learn more about how your HVAC system works here.

Why an AC compressor goes bad?

The main reason your AC compressor goes bad is that liquid refrigerant makes its way into the compressor.

It can be one of the reasons your AC system isn’t working.

If liquid makes its way into your compressor, it can be for the following reasons:

  1. You have too much refrigerant in your refrigerant lines

  2. You do not have enough airflow in your system

Too much refrigerant will prevent the evaporator coil from doing its job correctly, which is to evaporate all the refrigerant into a gas.

This leads us to the second point.

The goal of the evaporator coil is to convert the refrigerant from a liquid to a gas.

It does this through a heat transfer process.

If there is not enough airflow through your evaporator coil, then the “hot” airflow won’t be able to evaporate all of the liquid refrigerants into a gas.

There are a few reasons why your AC system will not have proper airflow.

One of the most common is dirty air filters, restricting airflow.

That is why checking and replacing your air filters regularly is essential.

Lack of airflow may also lead to your evaporator coil freezing.

If your evaporator coil freezes, it will prevent the warmer air from evaporating your refrigerant.

Eventually, the liquid refrigerant will make its way into your compressor, damaging it. This can happen slowly over time, due to increased strain on the motor. Or in a matter of a few days.

The increased strain on the motor can also damage the AC capacitor.

Another common reason for the lack of airflow is high static pressure.

High Static pressure is caused by ducting that is not properly sized or dirty air filters.

What are the different types of AC Compressors?

There are many various types of AC compressors.

The most common two in residential HVAC are reciprocating and scroll compressors.

A reciprocating compressor is more common and has been an industry standard for many years.

A reciprocating compressor works similarly to the pistons of a vehicle.

As the pistons move up and down, they compress the refrigerant.

Scroll compressors are newer, more efficient alternatives that are becoming a standard in new systems.

The way a scroll compressor works is a little more challenging to grasp.

It consists of two interconnected scrolls.

One scroll is stationary, and the other rotates on an axis.

It compresses and pushes the compressed refrigerant further down the scroll as the scroll rotates.

Once it reaches the center of the scroll exits the compressor as a compressed gas into the refrigerant line.

How Much Does it Cost to Replace an AC Compressor?

There are a few costs involved in replacing an AC compressor.

You need to account for the compressor, the labor, and the refrigerant.

A typical compressor replacement can cost anywhere between $800 to $2,800.

There are a few factors that contribute to the price, such as the type of compressor and the service location.

If you are in a more urban area where the cost of living is higher, then similarly, the cost of labor will be higher as well.

When contacting an HVAC pro, always be sure that the price they charge covers everything. You don't want any surprises.

It should include the cost of the compressor, the labor, and the refrigerant recharge.


Your AC compressor is a vital component in the operation of your HVAC system.

There are many reasons why your AC compressor may fail.

To replace an AC compressor, you will need the help of an HVAC professional.

They must have proper licenses and certifications when working with refrigerants.

Furthermore, you want to ensure your HVAC professional replace the compressor correctly. This involves evacuating the lines, creating a vacuum in the lines, and charging them with the proper amount of refrigerant.

Be sure to choose a reliable HVAC company when replacing your AC compressor.

The best way to ensure your compressor doesn’t fail often is by having yearly HVAC maintenance and replacing filters regularly. This will ensure your HVAC system is working correctly.

If your AC compressor goes bad for any reason, it can cost you anywhere from $800 to $2,800 to replace.

Don’t hesitate to contact us if you have any questions. We are always happy to help.

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