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In the same way, as we need our air conditioning unit to keep us cool during the boiling summer months, your air conditioner needs a functioning compressor to do its job properly.
In the event that a compressor suddenly gives out on a hot day, you will immediately become aware that your air conditioner is no longer producing anywhere near enough cooled air.
Failing to find the root cause can cause catastrophic failure of your AC and its components.
The reasons that a compressor can malfunction are numerous.
However, before we look at some of the most common ones, it is worth stopping for a minute to understand why the AC compressor is such an important component of a cooling system.
NOTE: The same information in this article can be applied to Heat Pumps.
⭐ Air Conditioner’s Compressor – What Is It?
Of all the parts that make up an air conditioning system, the compressor is probably the most important.
Here are a few basic points that you should know before reading the rest of this article:
The compressor is responsible for driving the refrigeration gases around the refrigerant lines.
Without it, you will have no cool air.
Compressors are quite durable and tend to last 15-20 years before they need replacing.
However, if you do not maintain it, the compressor may break down before this.
It is unwise to attempt to repair or replace a compressor without prior air conditioning experience.
Due to the delicate nature of an AC compressor failure, you should always call on the services of a licensed HVAC professional.
⭐ Common Causes of Compressor Breakdown
Now that we have clarified the crucial role of the air conditioner compressor, it is time to look at a few common reasons why they can malfunction.
️ Dirty Coils
As time passes, dust and dirt will naturally accumulate on an AC unit’s condenser coil.
This dirt can inhibit the efficiency with which the coil can perform heat transfer, meaning that the system has to expend more energy to reach the temperature dictated by the thermostat.
Clean coils can maintain a temperature differential of about 15-20°F between the refrigerant and the ambient air. However, dirty coils can reduce this differential, sometimes by as much as 30%, significantly decreasing the system’s coefficient of performance (COP).
When heat cannot escape, and the system is put under extra strain, the compressor tends to overheat and break down.
If you notice that your AC unit appears to be laboring, it is a good idea to clean the coils using special cleaning foam to see if this resolves the issue.
Replacing the air filter regularly helps protect the evaporator coil from accumulating dust and allows for better air flow over the coil.
️ Insufficient Refrigerant Charge
AC compressors produce cool temperatures by pumping a refrigerant gas called Freon around a series of refrigerant lines.
Refrigerant lines are sealed systems, and refrigerant levels should remain constant.
However, it may sometimes be the case that a refrigerant line develops leaks, which allows the refrigerant to escape.
When this happens, the system will overheat and sometimes cause your ac compressor to malfunction.
Refrigerant leaks can occur due to various reasons, such as wear and tear, corrosion, or improper installation.
These leaks can be difficult to detect without proper equipment, as the leaking refrigerant often evaporates quickly upon exposure to air.
If you suspect that your system has a refrigerant leak, you should call an HVAC professional to take a look straight away.
Unattended refrigerant leaks can damage your AC unit and are difficult to fix without experience.
️ Electrical Malfunctions
No electrical system lasts forever, and the same can be said for the circuit board and wiring in an AC unit.
Over time, acids and oxidation will build up and eat away at the contacts in the circuits and cause a power failure.
In the end, this will prevent power from reaching the AC compressor, causing it to shut down suddenly without much warning.
The air conditioning compressor, being a high-draw component, is particularly susceptible to electrical issues.
Voltage imbalances, even as small as 3-4%, can increase motor winding temperatures, potentially leading to premature failure.
Unless you are a trained electrical engineer, you will struggle to diagnose and repair an electrical malfunction.
On the other hand, an experienced HVAC technician can quickly replace the offending wire or circuit board for a reasonable price.
️ Clogged or Damaged Suction Lines
Another issue that can cause sudden compressor breakdown is problems with the suction lines.
When refrigerant lines get older, the constant change in temperatures they are subjected to throughout their lifespan can cause them to develop cracks and holes.
This thermal cycling can lead to fatigue, especially at bends or joints in the refrigerant lines.
Additionally, vibration from the compressor operation can exacerbate these issues over time.
In some cases, the expansion and contraction of the lines can cause small leaks at flare fittings or brazed connections.
Damaged lines can prevent the compressor from moving refrigerant around the system freely, reducing your system’s cooling capacity.
This restriction in refrigerant flow can lead to increased superheat at the compressor inlet and decreased mass flow rate through the system.
As a result, the evaporator may not receive sufficient refrigerant to maintain proper cooling, leading to decreased system efficiency.
This puts additional stress on the compressor motor as it’s working hard trying to pump enough refrigerant through the system and will often result in an eventual breakdown.
If you notice that your system is struggling to produce cool air, it Is worth having an HVAC technician come and check the suction lines for damage.
If they find anything, they can replace the lines and top the system up with Freon.
️ Inadequate Lubrication
Just like with any other motor, your compressor motor requires lubrication to keep all of its moving parts running smoothly.
In the event that your compressor motor is forced to run without being serviced with oil, it will not be long before it has worn out and needs replacing.
Insufficient lubrication can lead to increased mechanical friction, which can cause excessive wear on bearings, pistons, and other moving parts.
This can result in metal-to-metal contact, generating heat and potentially causing the compressor to seize.
You can often add lubricant to a compressor motor without prior AC knowledge or training.
Find the oil lubricant entry point on your compressor and add some of the same type of lubricant as recommended in the unit’s instruction manual (be careful not to overfill and check the lubricant levels while filling).
However, if the motor in your compressor wears out before you have a chance to do this, you will need the help of a professional to install a new one safely.
️ Contaminant Infiltration
If your house uses a central air conditioning system, the compressor will usually be located in the external unit outside your home or on the roof inside the condenser coils.
Unfortunately, exposure to the elements for prolonged periods gives ample opportunity for contaminants such as dust, dirt, leaves, bird droppings, and soot to find their way into your AC unit.
These contaminants can affect various components of the system, not just the compressor.
If this debris gets into the compressor, it may cause a malfunction.
Contaminants in the refrigerant circuit can lead to several major issues within the compressor.
Acidic contaminants may break down the lubricating oil, compromising its effectiveness.
Particulate matter can damage valve seats or interfere with proper valve operation, while debris accumulation in narrow passages can restrict refrigerant flow.
Certain contaminants may react with the refrigerant or oil, potentially forming harmful compounds that further degrade system performance and longevity.
To prevent contaminant infiltration, you should take care to clean the area around the external unit as well as inside it.
This routine should be performed every couple of months or so as part of a regular maintenance routine.
Extreme Temperatures
Overheating can cause an AC compressor breakdown. This can be caused by poor ventilation around the outdoor unit or extremely high ambient temperatures.
When the area around the condenser unit is cluttered, or the unit is placed in direct sunlight without adequate airflow, it struggles to dissipate heat effectively.
Similarly, during heatwaves or in consistently hot climates, the compressor may be forced to work beyond its designed capacity.
This prolonged exposure to high temperatures can lead to increased wear on internal components, breakdown of lubricating oil, and eventual compressor failure.
Proper ventilation and strategic placement of the outdoor unit can lower these risks.
️ Preventing Compressor Failure
Want to keep your AC compressor running smoothly and avoid costly breakdowns? Here are some simple tips that can make a big difference.
Regular check-ups are key. Have your AC yearly inspected by a pro. They can spot little issues before they turn into big ones.
Keep it clean. Change the air filters every few months. It’s an easy job that helps your system breathe more easily.
While you’re at it, give your outdoor unit some space by clearing out leaves, twigs, and anything else crowding it.
Pay attention to what your AC is telling you. If it’s making weird noises or not cooling like it used to, don’t ignore it. These could be early warning signs of compressor trouble.
Refrigerant levels matter. If your system is running low, it’s working harder than it needs to. If you suspect a leak, get it checked out immediately.
If your AC is turning on and off like it’s playing a game of tag, that’s called short cycling. It’s not good for the compressor, so get it looked at.
A little TLC goes a long way in keeping your AC compressor happy and your home cool.
If you’re ever unsure about something, don’t hesitate to call in an HVAC expert. Better safe than sweaty, right?
Compressor Types and Common Causes of Failure
Different AC systems use different types of compressors, each with its own potential issues. Let’s look at some common types:
Reciprocating Compressors
These use a piston mechanism to compress refrigerant.
- Common failure – Valve wear due to continuous up-and-down motion.
- Warning sign – Loud knocking noises during operation.
Scroll Compressors
These use two spiral-shaped scrolls to compress refrigerant.
- Potential issue – Bearing wear, especially if scrolls become misaligned.
- Red flag – High-pitched squealing sound.
Rotary Compressors
Often found in smaller systems, these use a rotating motion for compression.
- Typical problem – Seal failure leading to refrigerant leaks.
- Indicator – Gradual loss of cooling efficiency.
Screw Compressors
Used in larger commercial systems, they compress refrigerant using interlocking screws.
- Common concern – Oil management issues.
- Sign to watch – Unexpectedly high energy consumption.
Variable Speed Compressors
These adjust their speed to match cooling demands.
- Potential malfunction – Control board issues.
- Warning sign – Frequent cycling on and off.
DIY Troubleshooting Guide
Before calling in the pros, try these steps to diagnose your AC compressor issues.
- Check the thermostat, that it’s set correctly and has working batteries.
- Inspect the circuit breaker and reset it if tripped.
- Look at the air filter and replace it if dirty.
- Examine the outdoor unit and clear any debris and vegetation within 2 feet.
- Listen for unusual noises and not any clicking, rattling, or humming.
- Feel the air from the vents. If it’s not cool, there might be a compressor issue.
- Check for ice on the refrigerant lines; this could indicate low refrigerant.
- Observe the fan in the outdoor unit. If it’s not spinning, there could be an electrical issue.
Dealing with other common AC problems? Check out: Top 18 Common AC Problems and Solutions.
⭐ Conclusion
AC compressor failure can be one of the most costly issues for homeowners, but it’s often preventable with regular care and maintenance. Understanding the causes and signs of compressor failure can help extend your system’s lifespan and avoid uncomfortable breakdowns.
If your air conditioner isn’t cooling properly, don’t wait. Contact Vernon Air Conditioning, Plumbing & Electrical Services for expert AC diagnostics and repairs. Our highly trained professionals are here to keep homes across Vernon and the North Okanagan cool, comfortable, and energy-efficient.
📞 Ready for reliable AC service? Give us a call today or schedule a visit online. Your comfort is our priority.
