8 causes of HVAC compressor failure (and how to avoid them)

A heating, ventilation, and air conditioning (HVAC) compressor is a vital part of any HVAC unit. But what causes them to break down, and how can you prevent it from happening?

Compressor failure can be a costly issue for an HVAC system. The main thing is detecting the issue in time before it becomes an expensive problem. At Mid-Tech, we’ve compiled an extensive list to help you diagnose the problem early and ensure you prevent the issue from reoccurring in the future.

What does a compressor do in a HVAC system?

A compressor is the heart of your HVAC system. It’s responsible for compressing the refrigerant by allowing cool air to flow through an air conditioning system before removing heat (or cold air in the case of reversible air conditioning).

They can operate for 10 to 15 years if provided with proper care. However, failure to maintain your system will lead to an increase in wear and tear before potential HVAC compressor failure. Dust, debris, or refrigerant leaks can also hurt the functioning ability of your HVAC compressor over time.

In some unfortunate scenarios, you won’t be able to fix it, and you’ll be forced to replace it.

How does a HVAC compressor work?

Your HVAC compressor plays a vital part in the cooling process. The refrigerant collects heat from the evaporator and flows to the compressor before decreasing the refrigerant’s volume and turning it into a liquid state.

When a refrigerant is compressed, the temperature rises and transforms into a high-pressure gas. It then flows to the condenser coil to release the heat outside. Again, it’s converted into a liquid that flows to the indoor unit. This process is repeated to complete the refrigerant cycle.

To learn more about the refrigerant process, read our article: A complete guide to air conditioning refrigerants.

4 warning signs of a HVAC compressor failure

Compressor repair or replacement is costly, and you want to detect any problem that could lead to a compressor failure as soon as possible. So, here are four early warning signs that indicate your compressor is potentially about to break down.

  1. Reduced airflow is one of the early symptoms of compressor failure. The best way to identify a weak airflow is to feel under the vents. If you feel little to no airflow or feel warm air when it should be cool, this means the HVAC has a compressor issue.

    If this issue occurs, you should contact an HVAC professional immediately and get it fixed.

  2. If you hear your HVAC unit start making loud banging or growling noises and you notice vibrations, it could be a sign of compressor failure or another more serious issue.

    These noises indicate that the compressor is having trouble starting and may malfunction. The banging noise also signifies the failure of the electrical components in the compressor.

  3. The tell-tale signs of a refrigerant leak include weak airflow, hissing sounds, water around your HVAC unit or ice formation on the evaporator coils. Solving a refrigerant leak should become an urgent priority as it could lead to other problems later.

    A leaking refrigerant can impact your system’s cooling and cause compressor failure. Regular planned maintenance can detect refrigerant leaks early before it damages your compressor and requires fixing.

  4. If your compressor works harder to cool your environment, it will draw more power and run more often, drastically increasing your electricity bills.

    So, if you notice a sudden surge in your bills without increased usage, your HVAC system could be declining. If this is the case, arrange for your HVAC unit to be checked by a professional.

What causes HVAC compressor failure?

HVAC compressor failures are usually due to internal problems that impact the performance of your compressor over time. Here are eight common warning signs to look out for:

  1. An electrical failure can be caused by damaged contactors, wires, and fuses. Acids can build up in your system, resulting from electrical problems to cause other parts of your system to malfunction. Power outages can also result in electrical issues in your HVAC unit.

  2. A lack of maintenance plays a role in blocking your condenser coils. When clogged with grime and dust, they cannot release heat, applying pressure on the compressor. If you continue to run your system in this condition, your compressor can overheat and stop functioning.

  3. Overheating is a common cause of compressor failure with many potential factors. For example, if direct sunlight falls on your outdoor unit without adequate ventilation, the HVAC compressor can overheat.

    High voltages can damage the motor causing the compressor to overheat too. Plus, any dirty coils, low refrigerant levels, and lack of insulation all contribute to compressor overheating and eventual failure.

  4. If your air conditioning unit’s evaporator motor is displaced, it can force the refrigerant to return to the compressor. This issue pushes the compressor oil out of its place, and your system can face lubrication issues. The result? Your compressor will lose its efficiency over time, and eventually, it will cease to operate.

  5. You won’t cool your environment without adequate amounts of refrigerant in your HVAC system. A common misconception is refrigerant levels decrease over time. Rather than your air conditioner using up the refrigerant levels, it’s more likely it’s a leak that needs fixing.

    Low refrigerant levels decrease the pressure, causing the compressor to work harder when pushing the refrigerant within the system. Eventually, the entire compressor will collapse. Minimal maintenance can increase corrosion and cause cracks in the coils. Therefore, we recommend regular maintenance to avoid this issue.

  6. The refrigerant levels must match the quantity specified by the manufacturer. High refrigerant levels can lead to increased pressure in the system, causing premature compressor failure. The perfect refrigerant level is required to ensure your HVAC operates correctly and efficiently.

  7. Your HVAC needs the correct amount of lubrication to function optimally. Without regular lubrication, the wear and tear will increase, making your compressor work harder.

    When there are low levels of oil, your compressor parts rub against each other. This can cause parts to come loose and damage the system from within. A loss of lubrication is due to leakage from the evaporator, condenser, pipe connections, or the compressor shaft seal.

    An overstressed compressor is likely to break down earlier than its expected lifespan. Compressor parts rubbing against each other will create a burning smell. If this occurs, it’s crucial to get in touch with us.

  8. Outdoor pollutants, dust, debris, soot, and moisture can enter your outdoor unit and cause issues for your HVAC compressor.

    Air can also enter to dispel the refrigerant in the condenser. This issue will increase the temperature inside the compressor and can cause oil carbonisation on the discharge valve. Oil carbonisation results in residue build-up, causing valve leaks. Leaking valves further increase the temperature, causing more damage to the compressor.

How much does it cost to replace a compressor? 

A HVAC compressor has a lifespan of around 10-15 years. It is quite costly to replace, with the average cost of replacing a compressor being around £500.

Luckily, problems with the compressor can be detected early with this guide, to prevent you from having to break the bank. The next section will cover methods of preventing such failures to occur

Simple ways to prevent HVAC compressor breakdowns

If compressors fail before their expected life, the issue is internal and can be avoided with professional maintenance.

Here are several steps you can follow to prevent compressor failure:

1. Inspect the wiring

You need a regular professional inspection to check the wiring. Issues involving wiring can lead to acid accumulation which deteriorates many components of your HVAC system, including the most important one – your compressor.

During a routine inspection, engineers will check and replace faulty wires and fuses before they lead to acid build-up.

2. Keep the suction lines clean

Temperature and pressure changes can impact the normal operation of your compressor. When suction lines become blocked due to excessive dirt, the pressure and temperature increase, leading to overheating and failure.

3. Only call qualified professionals

An unqualified technician can pose fatal problems for your HVAC system, potentially affecting the health of occupants inside. As discussed above, they can fill the refrigerant too much/little, which can cause compressor failure.

Similarly, while repairing suction lines, they may install a short or long suction line which can interfere with the compressor pressure. HVAC repairs are a sensitive matter and should always be handled by experts.

4. Lubricate your system

Considering that the compressor is the heart of your system, keeping it lubricated is the key to its healthy maintenance. Regular lubrication will avoid compressor failure and keep your HVAC functioning correctly.

5. Frequent cleaning of coils

Air conditioning unit coils collect a lot of debris and need frequent cleaning. Failure to do so can interfere with the heat exchange process. When this happens, the compressor must do extra work to remove the heat.

Avoid HVAC compressor failure with Mid-Tech Services

Now that you know the various causes of HVAC compressor failure, the lesson is never to ignore any warning signs. The delay will not make the problem go away. It will only add to the damage.

If you can’t manage your system internally, we advise utilising a planned, preventative maintenance contract. This solution ensures that any underlying issues are fixed before further damage to any other part of the HVAC system.

Get in touch if you encounter any problems or need any further support. In the meantime, follow our journey on LinkedIn, Facebook and Instagram for more handy HVAC insights and news.

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