What Does an AC Compressor do and Should I Fix it?

AC Compressor Symtpoms Lack of Cool Air, Unusual Noises, Clutch Not Engaging, Refrigerant Oil stains

The AC compressor converts a refrigerant gas, changing it from low-pressure to high-pressure. Basically, when a refrigerant gas becomes high-pressure, it automatically absorbs heat because of physics. So, the compressor gets heat from the car's interior and releases it outside through this process.

The system couldn't produce cool air without the compressor, making your drive less comfortable on hot days.

Why is my car AC not blowing cold air?

Your car's AC might not be blowing cold air because of a few reasons:

  • Low refrigerant levels due to leaks or depletion.

  • A malfunctioning AC compressor.

  • Clogged or damaged condenser or evaporator.

  • Electrical issues, like a blown fuse or relay.

  • Faulty cabin air filter restricting airflow.

  • Thermostat or sensor problems.

A professional diagnostic check is recommended to investigate and diagnose the issue properly.

Why is my AC running but not cooling?

If your AC is running but not cooling, several factors could be responsible:

  • Low Refrigerant: The system might be leaking or be low on refrigerant.

  • Frozen Evaporator Coils: Restricted airflow or low refrigerant can cause the coils to freeze; this happens because the cold air gets stuck without airflow, so the temperature under the dash can freeze.

  • Dirty Condenser Coils: Dirt and debris can enter the AC system and reduce the coils' efficiency.

The AC condenser is clogged

  • Faulty Fans: If the fans aren't working correctly, the compressor won't be able to capture the heat and release it outside.

  • Thermostat Issues: Incorrect settings or malfunctioning thermostats can prevent cooling.

  • Clogged Filters: Old and dirty air filters can reduce airflow and make the cooling slow.

How long do AC compressors last?

Automotive AC Compressors Lifespan

An automotive AC compressor lasts between 60,000 to 70,000 miles. However, with regular maintenance and under good conditions, it can last up to 100,000 miles or more.

Factors Influencing Lifespan

  • Quality of the Compressor: High-quality, original equipment manufacturer (OEM) parts last longer than aftermarket parts.

  • Frequency of Use: Using the AC system regularly but not constantly can help the compressor last longer.

  • Maintenance: Regularly checking the refrigerant levels and ensuring no contaminants in the system can prolong the compressor's lifespan.

  • Driving Conditions: Driving in extremely hot conditions can put more strain on the compressor.

Signs of a Failing Compressor

  • Unusual Noises: Grinding or rattling sounds from the AC unit.

  • Reduced Cooling: The AC doesn't blow as cold as it used to.

  • Leaks: Puddles or spots of compressor oil under the vehicle.

  • AC Clutch Not Engaging: If the clutch doesn't engage with the compressor, the compressor can't circulate refrigerant.

Recommendations for Prolonged Lifespan

  • Have your AC system inspected regularly.

  • Ensure that the refrigerant is filled to the correct level.

  • Replace any damaged or worn belts connected to the compressor.

  • Use the AC system regularly to keep parts lubricated, but avoid overusing it always.

What causes car AC compressor failure?

Car AC compressor failure can result from various factors:

  • Low or Excessive Refrigerant: Incorrect refrigerant levels can strain the compressor, leading to potential failure as the lubrication for the compressor is suspended in the refrigerant, and a low refrigerant level will starve the compressor from lubricating oil.

  • Contaminants in the System: Dirt, moisture, or debris can damage compressor internals and hinder lubrication.

  • Poor Lubrication: Insufficient oil circulation can lead to increased wear and tear, which is generally a result of a low state of freon charge.

  • Electrical Issues: Faults in the compressor's electrical components, such as a short circuit, can cause it to malfunction.

  • Clutch Failure: The clutch drives the compressor. If it fails, the compressor won't activate.

The AC compressor clutch is failing because it lacks proper voltage

  • Age: Components naturally wear out over time, potentially leading to compressor failure.

Regular AC checks and preventive maintenance can reduce the risk of compressor-related issues.

How do you know if the AC compressor is bad?

There are a few common things that drivers might notice in their cars that indicate an AC compressor issue. Here are signs that it might be malfunctioning:

  • No Cold Air: The most evident sign is when the AC isn't cooling as it should.

  • Loud Noises: Unusual or excessive noises when the AC is turned on can indicate internal damage or wear.

  • Clutch Issues: If the clutch isn't engaging or is constantly engaged, the compressor may be at fault.

  • Leaks: Visible refrigerant leaks around the compressor area.

  • Circuit Issues: Fuses related to the AC system blowing frequently can be a sign.

  • Physical Damage: Signs of wear, corrosion, or damage on the compressor's exterior.

  • Poor AC Performance: Intermittent cooling or inconsistent airflow can hint at compressor issues.

If you notice these symptoms, it's recommended to consult with a professional technician for a thorough evaluation.

What should an AC compressor replacement service look like?

Some shops offer top-tier services that focus on customer satisfaction. Typically, these types of shops teach their customers about their car issues, going further to help them understand and prevent them.

We'll illustrate how one of these shops does an AC compressor service for a client; our story will be fictional but based on actual events.

A regular customer, John, pulled into Mike's auto shop complaining of a malfunctioning car AC. Mike himself took the lead on John's case.

Inspect: Mike looked around the AC compressor. Then, he took images of it using a high-resolution camera, photographing leak areas filled with oily residues.

Refrigerant fluid leak signs on an AC compressor

Test: Mike then initiated an AC performance system test. He looked at how the compressor reacted when the AC was turned on. Next, he checked the airflow, seeing that the cooling fans worked fine. Mike also put a thermometer in the vent with the AC. Finally, he saw that the vent temperature didn't drop to the degree he set in the AC console. So, he proved that the system wasn't working correctly.  

Evaluate: After noting all his observations, Mike sat with John to discuss the findings. Using the inspection images, he pointed out the oily residue, indicating a refrigerant leak and the wear on the compressor clutch. He created a collage picture comparing a new, healthy compressor with John's, explaining the differences.

Diagnose: With the pictures and test results, Mike proved that the compressor was failing and recommended a replacement. He explained that the wear signs, combined with John's described symptoms, made the diagnosis clear.

Confirm Repair is Completed: Once John gave the go-ahead, Mike replaced the compressor. After the replacement, he did more tests to ensure the system was fixed. Then, Mike shared post-repair images of the new compressor, comparing them with the previous photos.

John left the shop satisfied because he received proper attention, explanations, and transparent results. This hands-on, visual approach demystified a complex technical procedure for a car owner.

What are the top 5 causes of AC compressor symptoms?

1. Low Refrigerant Levels:

A decrease in cool air coming out happens. Low levels can strain the compressor, leading to its potential overheating and failure.

2. Electrical Failures:

The compressor may not activate. Faulty wires, blown fuses, or damaged relays can disrupt the power supply to the compressor.

The AC relays have melted along with the fuse box, causing AC compressor failure

3. Clutch Malfunctions:

Inconsistent or no cooling symptoms. The clutch controls the compressor's activation; if it's faulty, the compressor might not work.

4. Blocked or Leaking Condenser:

The AC has been cooling badly for a while. If the condenser is clogged or has leaks, it won't dissipate heat effectively, impacting the AC's cooling capability.

Refrigerant fluid droplets around the AC compressor indicate a freon leak

5. Wear and Tear Over Time:

The AC is slowly becoming worse. As with any mechanical component, the compressor will naturally degrade over time, leading to reduced performance and potential failure.

What are the top 5 fixes for AC compressor issues?

1. Refrigerant Recharge:

Refilling the system with the correct amount of refrigerant ensures optimal pressure levels and restores cooling efficiency.

2. Electrical Component Replacement:

Replacing faulty wires, fuses, or relays ensures a steady power supply to the compressor, enabling proper function.

3. Clutch Replacement:

A new compressor clutch ensures that the compressor activates and deactivates correctly, maintaining consistent cooling.

4. Condenser Cleaning or Replacement

Clearing blockages or replacing a damaged condenser ensures effective heat dissipation, improving AC performance.

Blocked Car Ac Condenser Vs. Clean Replacement

5. AC Compressor Replacement

In cases of severe wear or damage, replacing the entire compressor restores the system's ability to cool efficiently and reliably.


AC compressors play a vital role in cooling the vehicle cabin. However, it can have issues like low refrigerant levels, electrical failures, clutch malfunctions, blocked condensers, or natural wear and tear. Recognizing these problems and their symptoms early is crucial. Effective fixes range from refrigerant recharges and electrical component replacements to clutch or compressor replacements. Understanding these common issues and their fixes ensures better manageable care with the vehicle.

An auto shop near you delivers fair, transparent service like you've read here.

Feel free to visit our 'Shop Near You' page and search for our certified repair shops in your area. These businesses provide top-notch services and expert inspections using advanced diagnostic tools. You'll witness the same level of care and attention to detail highlighted in this article. These shops share our goal of ensuring your vehicle receives the best possible maintenance. At this goal's core, your knowledge of what's happening to your car and how to maintain it is our #1 priority.