bad AC compressor in air conditioning unit

What are the signs of a bad ac compressor? Sometimes, the air conditioner may continue to turn on and blow air from the vents even if the compressor isn’t working. Other times, the air conditioner may not turn on at all. Whether the air conditioner turns on or not, your house won’t be cool if the compressor is not working.

So, how do you know if the compressor is bad or something else is the issue? You could call an HVAC technician to inspect the air conditioning unit or try to diagnose the problem by doing some simple inspections and basic troubleshooting. Remember that if the compressor turns out to be faulty, you will have to hire a technician to repair or replace it.

What Is an A/C Compressor and What Does It Do?

The A/C compressor is a vital part of the air conditioner. It is often referred to as the “heart” of the system because it circulates the refrigerant through the system, and the system can’t function without it. The air conditioner can’t cool the house if the compressor goes down.

An air conditioner uses “refrigerant” gas to cool the house’s air. To do so, the refrigerant must go through a cycle, turning from a gas to a liquid and back to gas—the compressor and other parts of the air conditioner aid this process. The compressor applies heat and energy to low-pressure refrigerant until it becomes a high-pressure gas. This process allows the condenser to remove the refrigerant’s heat, turning it into a liquid. The refrigerant is pumped into the house to the evaporator coils, which absorb the heat and humidity from the home, turning the refrigerant back into a low-pressure gas. The refrigerant then travels to the compressor, and the cycle is repeated.

internal view of Copeland air conditioner compressor
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How Do I Know if My A/C Compressor Is Bad?

  1. You’ve noticed less air is coming out of your air vents.
  2. Your circuit breaker keeps tripping.
  3. You hear unusual noises like clicking or rattling.
  4. Your AC stops blowing cold air.
  5. Puddles or moisture around the HVAC system.
  6. Your air conditioner won't start.

Reduced Airflow

Reduced airflow is an early sign of compressor failure. If the air conditioner is running but less air or no air is coming out of the vents, a problem with the compressor is likely.

Circuit Breaker Problems

Circuit breaker problems can occur if the compressor is bad. Certainly, circuit breakers can be tripped if you run too many appliances at once, such as the TV, vacuum, washing machine, and air conditioner. However, if the A/C circuit breaker trips repeatedly, the air conditioner is probably an issue. A hot switch indicates a serious problem. Call an HVAC technician immediately.

Unusual Noises

A clicking, ticking, or chattering noise reminiscent of a gas stove burner's sound can indicate electrical problems. The compressor may have a faulty relay switch if it makes a clicking noise and is struggling to turn on.

When the compressor is starting up, rattling, rumbling, or clunking noises can indicate loose motor mounts. Motor mounts keep the motor securely in place and absorb vibrations. If the mounts are loose, the compressor motor bounces around, creating noise and vibrations.

Electrical and motor issues should be handled by a trained HVAC technician.

Lack of Cold Air

A lack of cold air from the vents can indicate several issues, including a dirty air filter, clogged condensate line, or refrigerant leak. Warm air blowing from the vents can also indicate compressor problems. You can rule out other issues by changing the air filter, clearing debris away from the condenser unit, cleaning the coils, and checking for clogs in the drain pans and condensate lines. If these measures don’t fix the problem, there may be an issue with the compressor or another issue like a refrigerant leak that requires the services of a trained technician.

Puddles or Leaks

It’s normal for some condensation to form on and around the indoor and outdoor units. The outdoor condenser turns the refrigerant into a cold liquid. When it’s hot outside, condensation can form on the copper lines and coils and drip off. A small amount of moisture around the unit that quickly dries up is normal. Condensation also forms on the evaporator coils in the indoor unit, drips into the drain pan, and drains through the drain line. If the drain line exits outside the house, it may be the source of a puddle around the outdoor unit.

If your air conditioner is leaking large amounts of water around either unit indicate problems. A puddle around the indoor unit can indicate a clog in the drain pan, the drain line, or frozen coils. An AC freezing up can happen for several reasons, one of which is inadequate refrigerant. When the coils freeze, the condensation turns to ice instead of evaporating. More condensation than usual is produced as the ice melts, causing puddles to form. The compressor needs the proper amount of refrigerant to function correctly. A Freon leak reduces the amount of refrigerant the A/C contains, and the compressor must work harder. The system will eventually stop working, and the compressor may give out. Refrigerant leaks are potentially hazardous to your health and the environment and can only be handled by licensed individuals. Call an HVAC professional immediately.

Air Conditioning Won't Start

Several issues can keep an air conditioner from starting up, such as a tripped circuit breaker, faulty wires, or a bad starter relay. You can rule out issues by checking the circuit breaker, changing the air filter, clearing debris away from the outdoor unit, and cleaning the coils.

A dead compressor will also prevent the system from starting up. As previously mentioned, the compressor is the system’s heart and can’t cool the air inside the home without it. If the compressor gives out, the system might shut down.

How Long Do A/C Compressors Last?

An A/C compressor can last 10 to 20 years. The compressor’s lifespan is usually shorter than that of the air conditioning unit and is affected by several factors:

  • Maintenance
  • Compressor usage
  • Size of the unit
  • Geographical location
  • Refrigerant leaks


Regular maintenance of the A/C unit will prolong its lifespan. Upkeep includes regularly changing the air filter and having the unit cleaned and inspected periodically so problems can be identified before the system fails.

The compressor’s lifespan is affected by how often it gets used. A compressor that is used too often can wear out; the pistons and motor can seize up if a compressor is used too little.

The compressor’s lifespan will be affected if the house’s A/C unit is the wrong size. The compressor must work harder to cool the home if the unit is too small. The compressor will repeatedly turn on and off to keep the house at the correct temperature if the unit is too large. Both situations can cause the compressor to wear out.

central air conditioner condenser unit outside of home sitting on grass against a brick exterior wall

Your house’s geographical location and climate affect the compressor’s lifespan. A compressor in the northern US can last 15 to 20 years, while compressors in southern states last 8-10 years since they receive more use.

Refrigerant leaks put a strain on the compressor and affect its lifespan. An A/C must contain the appropriate amount of refrigerant to cool the air inside the house. The compressor will have to work harder to pump refrigerant through the system if it loses refrigerant through a leak.

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Routine Compressor Maintenance Tips

Some of these maintenance tasks, such as changing the air filter, can be performed by the homeowner or business owner. However, other tasks should be performed by a certified HVAC technician. Routine maintenance of the A/C system will prolong the compressor’s life.

Clean Coils and Filters

Dirt and grime can collect on the coils, preventing them from adequately doing their jobs and making the compressor work harder. The coils should be cleaned periodically by a handy homeowner or a technician.

Changing the air filter is vital to the longevity of your A/C unit’s compressor. A dirty filter will significantly reduce airflow, which will cause the compressor to work harder and longer than usual. How often you change an air filter depends on several factors, but as a general rule, a homeowner should change their air filter regularly (every 45-90 days).

Check Refrigerant Levels

If you are experiencing a drop in the cooling power, have the refrigerant level checked by a technician. The compressor must work harder and longer to produce enough cold air to reach the thermostat’s set temperature if the level is low.


Avoid hitting the outside unit with the lawn mower or weed wacker; this can bend the metal fins on the unit and reduce airflow. Keep vegetation cut back two to three feet from the unit and clean leaves, twigs, and other debris out of the unit to improve airflow.

Keep Pets and Animals Away

Some animals like to mark on the compressor, which erodes the aluminum fins. Birds and rodents sometimes nest or create shelters in the unit. Protect the unit with a fence, but ensure it is accessible for service and allows good airflow.

AC Compressor Replacement Cost

According to HomeGuide, the average replacement cost of an A/C compressor is $1,000 to $2,500. Warranty, size, type, brand, and labor costs are all factors that determine the total replacement cost.

A compressor under warranty costs $600 to $1,200 to replace. A compressor out of warranty costs $1,300 to $2,500 to replace.

A compressor costs $400 to $1,300 depending on its size, type, and brand. Since HVAC companies charge $100-$150 per hour, the labor cost to replace a home AC compressor is $600 to $1,200.

Tonnage Total Cost

1.5 - 2 Tons

$1,000 – $1,250

2.5 Tons

$1,100 – $1,600

3 Tons

$1,200 – $1,750

3.5 Tons

$1,250 – $1,900

4 Tons

$1,350 – $2,100

5 Tons

$1,450 – $2,300

6 Tons

$1,650 – $3,000

*For both materials and labor in 2020.

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What Should I Do Next?

If you suspect the A/C compressor is bad, call an HVAC technician. A technician will inspect the unit and perform any necessary repairs. Replacing the compressor is a job that a professional HVAC technician must do.

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1 comment

Elaina D'Agostino

Elaina D'Agostino

I appreciate your advice about fencing the compressor. As you said, animals can get in sometimes and create nests or shelters inside. This is what happened with ours. We just noticed rodent droppings near the compressor, so I think they’re inside. We’ll get the unit inspected and repaired, then we’ll get it fenced.

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