6 Recurring Causes of AC Compressor Failure (and What to Do About Them)
Home Improvement

6 Recurring Causes of AC Compressor Failure (and What to Do About Them)

Emergency home spending repairs represent a significant threat to the homeowner’s budget. For one thing, they’re difficult to plan for. After all, you can try to set aside a little extra money in case unexpected expenses arise. However, this is hard to justify when you have actual expenses to meet right now. For another thing, emergency home spending repairs tend to be costly. For American homeowners, the average cost of home emergency repairs, including HVAC repairs, was $1,640 in 2020. AC compressor failure is a common problem requiring emergency HVAC repair. As such, it can significantly impact your family’s budget. Fortunately, there are steps you can take to make this problem less likely. Read on to find out more about AC compressor failure signs, solutions, and prevention.

What Does an AC Compressor Do?

The AC compressor really is your unit’s heart. First, like the human heart, your AC compressor is crucial to your AC unit’s continued functioning. When the AC compressor fails, the unit will too. Second, just as the human heart pumps blood, the AC compressor pumps an essential fluid—refrigerant—through the system. In a well-functioning AC system, the refrigerant begins its journey in the outside unit. At this point, it’s a cool liquid. The compressor’s job is to pump this initially cool liquid to the unit inside your home. Once inside, the refrigerant absorbs heat from your home. As it does, it turns into vapor. After it’s gathered all the heat it can hold, this vapor returns to the outside unit. Back at the unit, the compressor takes in the refrigerant vapor and heats it further. Doing so makes the vapor a superheated gas that’s even hotter than the air outside. Since heat naturally transfers to cooler spaces, the vapor cools and returns to a liquid state. At this point, the compressor begins the cycle again.

What Are Common AC Compressor Failure Symptoms?

Recognizing the signs of AC compressor failure is important to maintain your comfort and prevent more damage to your system. The most obvious sign of AC compressor failure is a compressor that doesn’t turn on. Usually, though, you’ll notice other changes first. These include:
  • Diminished airflow
  • Warmer air
  • Moisture leaks
  • Ice collecting on the cooling coils
  • Strange noises
The most common AC compressor failure sound is a ticking, rattling, or hissing noise. In fact, a ticking sound can be an early warning sign of AC compressor failure, as the compressor struggles to turn on. Rattling noises, in contrast, could indicate loose parts inside the compressor. Finally, hissing noises can indicate a leak in the refrigerant lines.

What Causes AC Compressor Failure?

Compressor failure can stem from several problems. Knowing the most common AC compressor failure causes can help you diagnosis your system. It can also help you prevent problems before they start.

Inadequate Refrigerant

Your system needs an adequate supply of refrigerant to cool your home. When refrigerant is low from a leak, the compressor must work harder. This undue stress can cause the compressor to fail. Remember that hissing or bubbling noises suggest a leak in the refrigerant lines. If your system is struggling to cool your home, listen carefully for these noises. Also check for ice or condensation on the cooling coils. If any of these signs are present, contact an AC repair service right away. A qualified repairman will check your refrigerant levels, ensuring that they are neither too low or too high. A qualified repairman will also choose the right type of refrigerant for your system.

Inadequate Lubricant

Oil levels in your AC unit can also be low. Without adequate oil lubricant, the system won’t work properly. Again, this stresses the compressor and can eventually cause it to fail. A qualified repairman can help you check and maintain the oil lubricant in your AC system.


The compressor is part of your AC system’s outdoor unit. As such, it is vulnerable to contaminants. These include moisture and air. They can also include soil, leaves, and other debris from your yard. Bird droppings and soot are other common problems for AC compressors. If any of these contaminants enter the compressor, they can damage the mechanism and cause it to fail.

Dirty Coils

Dust and debris can collect on another important part of your AC unit: the condenser. When it does, the unit struggles to push enough air through the system. As a result, it runs constantly. The increased pressure and temperature, in turn, can cause the compressor to overheat and, ultimately, fail.

Suction Line Blockage

Another cause of increased pressure and temperature in the compressor is a suction line blockage. This problem, too, can cause the compressor to overheat and fail. If you do need to replace the suction line, be sure to work with a qualified professional. An expert repairman will choose the right size replacement line. Choosing a line that’s too small or too large can lead to premature compressor—or even system—failure.

Electrical Problems

Electrical burnout usually signals the death of an AC compressor. When an electrical failure occurs, acids build up in the system. These acids cause significant damage to the compressor. An AC repairman can check for the presence of these acids. If he finds them, burnout has caused the compressor to fail, and it’s likely not worth fixing. However, an AC repairman can also check for electrical problems, like damaged wiring and fuses, before they become fatal.

Preventing AC Compressor Failure

The best way to deal with AC compressor failure is to prevent it from happening. Fortunately, this takes just a little bit of planning and effort. As with most appliances, adequate maintenance is the best prevention. At a minimum, maintaining your AC unit means replacing the air filter at least every 45-90 days. If your unit has a high-pressure switch, engaging it during the hottest periods of the year can also reduce the stress on the compressor. Another step you can take at home is to give your AC unit some space. In other words, keep the unit clear of branches and shrubs. If necessary, trim any overgrowth to let your compressor breathe and keep it clear of contaminants. Also check around the unit for collections of other debris, like dirt and leaves. Finally, it’s important to clean the AC unit, especially the condenser fins, of accumulated debris. You can read about DIY methods for this process online. However, it can be tricky and dangerous for you and your AC unit if you attempt to do it yourself. That’s why the truly best solution—for AC diagnostics, repairs, and preventative maintenance—is always a qualified AC repair service.

AC Trouble: Keep Cool and Carry On with These Steps

AC compressor failure is a costly problem that can impact your family’s comfort and safety. Knowing the signs and common causes can help you identify this problem as soon as possible. Early detection, in turn, can reduce the cost and complexity of repairs. Even better than early detection, though, is prevention. Now that you know how to maintain your AC unit’s compressor, it’s up to you and a qualified repair service to keep it healthy. As you work to maintain and improve this and all aspects of your home, count on our blog for the best advice!

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