Symptoms of Bad AC Compressor in Car: Diagnose and How to Change?

The AC compressor is an essential component of your car’s air conditioning system. It plays a significant role in pressurizing and keeping the air refrigerant circulated so that you can have an optimum operating air conditioning system. The AC compressor works by switching ON and OFF continually, making it prone to wear and tear whenever you turn it on. Just like any mechanical component in your car, it tends to fail over time and needs replacement.

When the car AC starts wearing out or failing, it will show symptoms of a bad ac compressor to tell the driver that it has a problem and needs to be changed. Since the AC compressor is responsible for pressurizing and circulating the AC refrigerant, a problem with it will negatively affect the entire air conditioning system. Before you go any further, here’s what you’ll learn; how to tell if a car’s ac clutch is bad, what the AC compressor does, and how to diagnose and replace the car’s AC compressor.

bad car ac compressor symptoms

What does the AC compressor do?

Car ac compressors have made driving a pleasurable experience since the early days of the automotive invention. As technology advances from time to time, the production of cars becomes easier, and as a result, vehicles are sold at affordable prices. One of the inventions as a result of this advancement in the automotive industry is the invention of the AC system, which makes driving fun for people in the humidity depth of the summer season.

As the car ac system was introduced in the automotive industry, which allows commercials and families to travel from one place to another in a comfortable temp, you can lower your vehicle’s inside temperature. So, what is an AC compressor in a car, and what does it do? The compressor is the power unit of the air-conditioning system that pressurizes refrigerant before sending it to the condenser which transforms the refrigerant from gas to a liquid state. Without the AC compressor, the air-conditioning will not work optimally.

Symptoms of a bad Ac compressor in a car

Identifying symptoms of a bad Ac compressor in a car is not as difficult as it may seem. In fact, bad ac compressor signs are simple and Crystal-clear to identify. Some symptoms will pop up when you have a lousy ac compressor. Watching out for these signs will help you diagnose and replace your AC compressor and save you from repair costs.

  • High cabin temperature
  • Loud noise from the AC compressor
  • Moisture leak
  • Is the compressor clutch stiff or not moving
  • Tripping circuit breaker
  • Broken Suction Lines

will a bad ac compressor affect the engine

High Cabin Temperature:

One of the first signs to know you have a failed AC compressor is when your dashboard AC vent is no longer sending cold air inside the car. A failed or bad air conditioning compressor will not circulate refrigerant in the air-con system, and the outcome will be warm air coming through the AC vents. So, when the AC compressor fails, you’ll notice high degrees and hot airflow inside the car. However,  there are three possible reasons behind the hot airflow inside your vehicle; the first could be a refrigerant leak, the second is a low refrigerant, and the third is a failing AC compressor that needs replacement.

Loud noise coming from the AC compressor:

When your vehicle’s ac conditioning system operates, it produces a clicking noise when switching ON and OFF. But if you notice loud noise when the compressor switches ON, it’s a sign your AC clutch is bad. The ac clutch is a vital part of an ac compressor that drives the belt that connects the AC compressor to the engine pulley. And when it fails, it can either seize or run freely, thereby making a hell of a noise.

Also, the AC compressor is made up of various interior components and utilizes a sealed bearing to spin. If the internal bearing is damaged or seized, or any of the interior components fail, it will produce all sorts of noise. The ideal solution is to diagnose and see if the clutch is the culprit or if the compressor is damaged and replace it.

Moisture leak:

Most people who ask, can I drive my car with a bad ac compressor don’t know the effects of moisture in-vehicle ac compressor. The air conditioning refrigerant helps the AC system cool down warm air, and if the AC system runs out of refrigerant, your AC will only produce warm air. Refrigerant leaks do not only increase harmful health concerns it also causes energy consumption. Refrigerant leaks are significant symptoms of a bad ac condenser in a car.

Compressor clutches stiff or not moving:

The compressor clutch connects the compressor to the engine pulley with a serpentine belt; it also allows the compressor to engage and disengage from the engine power so that the compressor will only spin when it has to. If the clutch fails, seizes, or is damaged, the compressor will no longer receive engine power.

The good news is, that the AC clutch is a separate unit; after diagnosis, you can decide to replace the clutch or the whole compressor unit. Since the clutch is a separate unit, you can save some cash and replace only it.

Tripping circuit breaker:

If your vehicle’s outside condensing unit keeps tripping the circuit, it indicates a lousy or failing ac compressor. This is because the compressor is overheating and drawing much power resulting in tripping the circuit breaker. Suppose you notice your circuit breaker is tripping, do not keep resetting it and switching on the system. The circuit breaker is only doing its job and protecting you and your vehicle from a fire outbreak.

Broken Suction Lines:

Your vehicle refrigerant line can block when you have a failed or damaged ac compressor resulting in hot airflow from your air vent. Unblocking refrigerant lines requires an HVAC expert’s assistance, or you might decide to replace the lines if you trust your gut.

How to diagnose car AC compressor

After noticing one or more signs of a bad AC compressor above, you might want to know how to test a car ac compressor so you won’t end up replacing a well-functioning compressor unit. Here are a few easy and straightforward ways to diagnose your car’s ac compressor.

  • Check temperature fluctuations
  • Check physical damage and oil leaks
  • Check if the clutch rotates freely
  • Listen for squealing and skipping noise
  • Check refrigerant leaks

Step 1. Check temperature fluctuations: If you are getting warm air when your AC system is engaged, chances are you have a lousy or failing ac compressor. If the AC is still working, check if the AC temp fluctuates; if it does, it’s an indication of a failing ac compressor.

Step 2. Check physical damage and oil leaks: Visually inspect your vehicle’s ac compressor for rust, physical damage, and oil leaks. These signs indicate a lousy or failing car ac compressor. Compressors with oil leaks will not work optimally and can even cause premature failure. Low oil in ac compressor resulting from a compressor leak will cause friction leading to erratic temperature when the air conditioning system engages.

Step 3. Check if the clutch rotates freely:  Inspect the AC compressor clutch and ensure it’s not making a grinding noise when turning or hard to turn. The clutch should turn freely. A lousy clutch can damage your entire compressor unit.

Step 4. Listen for squealing and Skipping noise: Start your engine, turn the AC to the coolest temp, and set the fan on max. Open your hood and pay close attention to the compressor clutch; check if the compressor unit engages. A lousy compressor unit may not engage, which can lead to squealing and Skipping noise.

Step 5. Check refrigerant leaks: The AC refrigerant in your vehicle should be intact and not leak for any reason; neither should you have low Freon in the car. Low Freon indicates a leak in the air conditioning system, and you should track down and fix it. You can easily track down refrigerant leaks using an electronic AC refrigerant detector.

How do you change an ac compressor?

As the name indicates, the AC compressor compresses the refrigerant into a high car AC pressure and circulates the gas within the air conditioning system. Without the AC compressor, the refrigerant won’t circulate in the AC system, and you will notice your air vent not blowing cold air. Without further ado, let’s get started with how to change the car’s ac compressor.

Things and materials needed:

  • Thread lock
  • Screwdriver drivers
  • Pliers
  • Ratchet handle
  • Universal joint socket
  • Wrenches
  • Socket sets
  • Clean rag
  • Compressor oil
  • Refrigerant
  • Cup bolts

Step 1. Removing the compressor unit from the engine bay

First, take off your battery negatively terminal so you won’t have a jolt of electricity or get a short circuit. Remove any covering on your engine so you can access the serpentine belt. Take the right tool from your mechanic tools box and pry the belt tensioner, and the belt will slip right off. Locate all the tubes and hoses on the compressor and disconnect them. Depending on your vehicle model, there may be other components or accessories blocking easy access to the compressor. Grab the proper wrenches and remove these components by loosening and disconnecting the bolts and wirings.

Ensure you have a cup bolt where you put all the bolts and connectors you removed from the engine. Locate the high and low-pressure lines on the compressor and unbolt the fittings. Take a piece of clean rag and block off the ends of the refrigerant lines so that dirt and grits will not enter the hole. Locate the electrical connector on the compressor unit and pry it off with your flat head screwdriver. Now, it’s time to get right on the lower and upper mounting bolts using the correct sockets and ratchet handle.

You might also need a universal joint socket to loosen the mounting bolts. First, break free all the bolts before loosening them. You need to hold the AC compressor unit by hand while taking off the last bolt, so you won’t wind up causing hazards to yourself or the compressor.

Step 2. Inspecting the old compressor

It is necessary to inspect the old compressor unit before disposing of it. By so doing, you will find out why it failed. If you hear a grinding noise when spinning the compressor clutch, that’s an indication there are metal shavings that need to be flushed right off. Get an air conditioning flush kit from any reliable or local store and unblock the orifice tube or expansion valve. Inspect the exhaust ports and refrigerant lines for metal shavings and clean them. You might have to change the orifice tube if it seems wholly blocked.

Step 3. Accessing the new ac compressor

Bring the new and the old compressor units close and access them. They may vary slightly in design as there are many AC compressor manufacturers, but the installation process should be the same. The exhaust and the intake port must be the same. Check the AC clutch outside diameter and the number of ribs on it. Check if there are accessories on the old compressor that are not on the new unit and transplant them. Check the new compressor user guide and see if it has pre-added oil; if not, add the recommended amount of oil. Take your wire brush, clean the old bolts, add some thread lock if you want to, and mount the bolts on the new compressor.

Step 4. Replacing the O rings

The compressors’ high and low-pressure refrigerant lines utilize o rings to ensure there are no refrigerant leaks. When replacing your vehicle’s ac compressor, you need to replace those seals to prevent refrigerant leaks.

Head over to both high and low refrigerant lines, carefully remove the old seals, replace them with ones, and rub the oil. The new o rings should match the refrigerant lines like the old ones. Do you want to proceed without replacing the old o ring? That’s not a good idea; it can cause refrigerant leaks.

Step 5. Mounting the new compressor

Take the new compressor to the engine bay and place it on the compressor sitting where you removed it. Fix the compressor and snug bolts by hand and later torque the bolts with sockets or wrenches. Take off the blockage on the high and low refrigerant lines and install them; ensure both lines are well-tightened. Install all the accessories you removed earlier, such as the electrical connector, serpentine belt, and any component you removed, to access the compressor unit. Then, take the final step by filling the refrigerant into the AC system. Watch this YouTube video for a visual clarification on Car ac compressor replacement.


Q: How long should a car ac compressor last?

Ans: As long as you have a desirable driving experience and your vehicle is running optimally, you might not bother to know the components and accessories working in the engine compartment. As many air conditioning components make up the AC system, it is hard to say how long the AC compressor can last accurately. The answer depends on age and how often you use your car ac. As you drive your car for a long time, the AC compressor will start malfunctioning. However, you can expect your AC compressor to last 8-12 years.

Q: How much does it cost to replace an air conditioner in a car?

Ans: The cost of replacing or fixing an air conditioner in a car varies significantly from vehicle to vehicle. Minor ac repair like refilling refrigerant and replacing sensors and hoses can cost $200 to $700. On the flip side, major ac repair like replacing ac condenser, compressor, or evaporator can cost $400 to $3500. The variation in replacement cost depends on your vehicle, location, and the garage you go for the replacement. A mechanic can charge $150 for replacing ac compressor, and another mechanic will charge $400 for doing the same job.

Q: Can I replace the car ac compressor myself?

Ans: Car ac replacement should be done by an HVAC expert. However, suppose you’re a competent DIY and confident enough. In that case, you can follow the guide in this article to successfully replace the AC compressor and save a decent amount of repair cost.

Do you need to replace the dryer when replacing the car ac?

Ans: It is essential to replace the dryer when changing the car ac compressor unit. In fact, most warranties recommend you to change the AC dryer whenever you work on the AC conditioning system.

Final word

If you notice the symptoms of a bad ac compressor, the next thing you want to do is carry out a car ac compressor diagnosis to be sure the AC compressor is the culprit. Replacing a vehicle ac compressor yourself can be an expensive, time-consuming fix. The ball is in your court to decide whether or not you want to replace the AC compressor yourself. The fact is, the summertime can get incredibly hot. Sweating and driving during a hot afternoon might not be something you want to experience.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

4 thoughts on “Symptoms of Bad AC Compressor in Car: Diagnose and How to Change?

  1. Bright, thanks for reaching out.

    The noise you hear from the AC compressor is a sign of a failing compressor clutch or a lousy pulley. Have a technician fix it.

  2. I have same problem with my ac compressor I hear lousy noise but the ac is working perfectly. Can I still use the car?

  3. Hey
    Christos Karlettides
    We’re absolutely delighted to receive such positive feedback! It’s our pleasure to provide valuable content that resonates with our readers. Your encouragement motivates us to continue delivering high-quality articles focused on automotive care. Understanding the symptoms of a bad AC compressor in a car is crucial for maintaining your vehicle’s air conditioning system. Look out for signs like strange noises, weak airflow, or warm air coming from the vents, as these can indicate a failing compressor. Regular maintenance and prompt attention to these symptoms can prevent further issues and ensure a comfortable driving experience. Thank you for following our work!
    Rx Mechanic Team

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