Aircon compressor

What is Aircon Compressor & How it Works?

The aircon compressor is one of the vital parts of an air conditioner. It helps to regulate the temperature and humidity level inside your home or office building, making sure you are always comfortable.

But what exactly does a compressor do?  What makes it so important for our daily life? Here’s everything you need to know about this amazing device!

What are aircon compressors?

Compressors move the refrigerant in between the evaporator and condenser coils. This ensures the refrigerant will change into either a liquid or a gas as it is needed.  The compressor can be thought of as the heat of your air conditioning system, and the blood is the refrigerant. So the refrigerant is pumped through the system by the compressor to keep it running correctly and alive and well.

The AC compressor is the system component that increases the vapour refrigerant’s pressure and temperature. The compressor needs to increase the vapour refrigerant’s pressure so that a pressure difference is created.  

How Do Aircon Compressors Work?

Whenever refrigerant leaves the evaporator of the air conditioner, it turns into a low-pressure gas. In order to release the heat that the refrigerant has absorbed,  it is essential for the refrigerant to be in higher pressure, higher temperature form. Molecules are packed tightly together in a gas-based refrigerant by the compressor. 

The process increases the refrigerant’s pressure and temperature. Heat moves from warm over to cool surfaces, so the heat inside the high-temperature refrigerant moves over to the cooler outdoor air so it can be released via the condenser. 

The compressor is located inside the condenser unit. It is the part that begins the chain reaction to cool the refrigerant. It is important to note that heat moves in the direction of cooler areas. Whenever the room temperature goes through the evaporator, heat is taken out of the air. The heat in the air is passed to the refrigerant and then fed to the compressor. 

Next, the refrigerant is compressed and condensed into a fluid. Then under pressure, it is released. At that point, the refrigerant is a lot hotter compared to when it came in. However, the heat is dissipated via the condenser coils.

Once the refrigerant has reached the end of the loop, it will be cold once again and fed to the evaporator coils. The cycle continues as long as your AC is turned on. Some AC systems have compressors where this process is reversed, with the output becoming hot air rather than cold air.

What Are The Differences Between Compressors And Condensers?

AC compressors are a type of mechanical device that lowers the gas volume so that pressure is added while the AC condenser is taking the pressurized gas and transforming it into liquid-vapour form.

Compress means reducing in quantity, volume, or size. But to better understand the way AC compressors work, you first need to understand how refrigeration works. To keep things brief, refrigeration makes it possible for an air conditioner to eliminate the heat inside your house and transfer it outdoors. The process warms or cools down your indoors, depending on what time of year it is.

AC condensers are designed to transform heat into a secondary fluid from a working fluid. It depends on the heat being transferred during the phase change. When the vapour enters into the condenser, it is at a higher temperature than the secondary fluid. Then the vapour cools down when it reaches its saturation temperature, is transformed into a liquid, and then released outside.

Is Replacing the Aircon Compressor Worth It?

The compressor is one of the most expensive and vital parts of the air conditioner.  It also has a relatively long lifespan and hardly ever dies in newer systems.  Older compressors also tend to be more power-hungry than newer ones. Depending on how old your air conditioner is, it would probably be best to invest in a new AC rather than replacing the expensive part.

You should, however, choose to have the compressor replaced if still under warranty. Other than this, you will have to foot for the total cost of the compressor and its installation charges. 

If this is the case, it will make perfect sense to top up some more money and invest in a new AC unit instead of replacing the compressor, which is quite expensive itself. Newer units are undoubtedly more energy-efficient and reliable as compared to the other generation air conditioners.

Is It Possible to Replace Just the AC Compressor?

As mentioned before, the compressor is a crucial component of the condensing unit (outdoor unit). It would only be advisable to replace only the compressor if its warranty is yet to expire.  If not under warranty, your next best option would be to replace the entire outdoor unit. You could replace the compressor only if:

  • You have a tight budget
  • You only have to foot the labour costs (if the compressor is on warranty)
  • The other components/parts of the unit are intact.
  • The indoor unit was recently replaced.

You could also consider replacing the compressor alone if everything else is still under warranty. With the compressor on warranty, your only expense will be the labour costs, which is close to nothing compared to the new compressor or unit price.

Be sure to take all factors into account (labour, time, and materials needed) if looking to take this route. The process of replacing a compressor is time-consuming and quite challenging.

Replacing the outdoor unit might be the smartest idea if the unit isn’t on warranty.  Although you might be tempted to replace the faulty component alone, the cost of a new compressor, additional materials, and labour will be almost the same as getting a new unit.

A new compressor will most likely come with a limited warranty (between 1 and 2 years).  The chances of the unit failing a year or so after replacing the compressor are pretty high. The risk of facing the same issue in a year or two’s time is simply too much for most people.

What Happens When the Compressor Fails?

The compressor’s main role is to maintain the pressure of the refrigerant and flow throughout the system.  Without it, the AC wouldn’t be able to keep your home/car cool. 

The compressor normally cycles on and off as required to keep the refrigerant pressurized.   Continuous cycles thus subject moving parts to constant wear and tear with prolonged use. Its efficiency may thus reduce over time with continued use of the air conditioner. You may thus need to have the compressor or unit replaced if it dies.

Your compressor will, however, give warning signs several months or even a year before it fails. 

The first sign to watch out for is the AC’s inability to keep your home or car cool like it used to. The unit might also start producing strange sounds, among other signs.  You, however, shouldn’t run to conclusions if the AC seems to struggle to keep your home cool.

Several other factors (a leaking refrigerant, low oil levels, etc.) should be eliminated first before settling for the compressor. Only a certified AC technician can ascertain the compressor’s condition and status.

What Next After A Failed Compressor?

Some AC compressors will fail as a result of a mechanical problem. This mostly happens when the compressor locks, producing a loud buzz and shudder before coming to a halt. Interestingly, you won’t find a failed or open short on investigating.

If this happens, your only options will be to see if the compressor can be replaced or invest in a new unit.  However, a series of tests should be done to ensure other parts aren’t to blame or haven’t been affected by the same.

The best way to approach this would be to call an AC service technician to check for you. The technician is better placed to handle this as he/she has the technical know-how and tools needed for the job.

Should the technician confirm the worst, he/she will either recommend relacing the compressor or a new unit entirely. The technician will also be able to verify if the compressor is still on warranty or not.

You will be required to foot for a new compressor and labour cost if the unit is out of warranty. Ask the technician to confirm the total cost of replacing the compressor, then compare it with the cost of a new unit. 

Consider replacing the compressor if it costs less than 50% of the price of a new unit. Only consider investing in a new AC if the cost of replacing the compressor is significantly higher.

Related read: Do aircon compressors need servicing?


If you want to know more about aircon compressors, give us a call. We can help with any questions or concerns that you might have, and we’re happy to provide some free advice on what your next steps should be if the compressor fails.

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