AC Compressor Clutch – How Do You Diagnose And Repair It?

AC Compressor Clutch – How Do You Diagnose And Repair It?

It’s a regular day and your car is working just fine. The heat is getting to you so you decide you need a blast of cool air. You turn the air conditioner on but to your dismay, you are welcomed with a breeze of warm air. Nothing could be more disappointing than this. What is the problem… Could it be the AC compressor clutch?

If your AC stops functioning properly all of a sudden, chances are, the compressor clutch has stopped working – it isn’t engaging anymore. The issue could be a small or serious one. If the clutch doesn’t engage, it usually means there’s a mechanical or electrical error in the compressor.

If the AC stops providing cool air, you might want to perform a visual inspection of the part, and figure out what might be causing this issue. Sometimes, the problem may be with the externals.

You’ll get warm air if the AC compressor doesn’t work (and if you want to know how to make AC colder in car), even if you’ve just filled the system up with refrigerant. You can check the engine oil and engine coolant too to rule out any other possibilities, but the most important component is the AC compressor clutch.

We’ll talk in length about why a compressor clutch won’t engage, how to diagnose it, and how to fix it as well…

AC Compressor Clutch

AC Compressor Clutch

If the air conditioner isn’t running to blow cool air inside the car, the pulley attached to the compressor freely spins. It does so to consume only a bit of the power that would normally be used in the process, giving you better fuel economy. But when you turn the AC on, this changes.

The role of the compressor clutch is to convert energy from the engine and supply it to the compressor. When the air conditioning is turned on, it engages the clutch and it starts spinning to begin transferring power.

In addition, the compressor clutch stops the AC from running 24/7. If it ran all the time, there would be a noticeable reduction in fuel economy; not to mention more chances of worn-out components. It would also exert too much strain on the engine.

What Is An AC Clutch

The modern compressor clutch is the heart of the newest completely automated temperature control systems in vehicles. The temperature within is controlled by a thermostat. When the level crosses the preset margin, a switch turns off, supplying the clutch coil with electrical current. This current generates a powerful “flux” or magnetic attraction around the coil.

The flux crosses the air gap between the rotor’s outer pole and the field, where it finds a “flux pole,” otherwise known as an air slot in the rotor. Then, the flux engages with similar sections in the armature, bringing the armature plates in an inward direction through magnetic force. It continues to move through the rotor’s inner pole, rotor/armature flux poles, and field assembly.

The rotating rotor is belt-driven via the engine. Similarly, the armature plate is attached to the compressor shaft. Once the rotating rotor magnetically attracts the plats, the compressor is engaged. Finally, the air conditioning system is brought to life and fills the vehicle’s interior with cool air.

The AC compressor clutch is located in front of the compressor. Once the air conditioning is turned on, the clutch is engaged and spins. If you want to find the AC compressor, it should be in front of the engine alongside the other belt-driven bits.

Bad AC Clutch Symptoms

As air conditioning is something most car owners use every day, it’s not hard to detect when there’s an issue with the system. Here’s how you can tell that your AC compressor clutch isn’t working.

AC Compressor Clutch, Symptoms Of Failure #1. Elevated Cabin Temperatures

Perhaps the most common symptom of a bad compressor clutch is elevated cabin temperature. Anytime there is an unexpected rise in cabin temperature, you can be looking at a defective compressor. The compressor will malfunction if the clutch is damaged, as it can’t regulate the flow of refrigerant anymore.

That being said, higher cabin temperature can be linked to the inadequacy of refrigerant too, so it’s essential to diagnose the system properly.

AC Compressor Clutch, Symptoms Of Failure #2. Loud Noises

The moment you turn the air conditioning on, a loud noise booms through the car. This is a sign of compressor clutch failure. Similar to the engine, the compressor is comprised of numerous moving components. Noises are a common phenomenon of the clutch, as well as its other parts when they start to seize or fail.

In addition, a leaking or worn-out bearing can produce a high-pitched squeal too. On the other hand, a grinding noise is created by a seized bearing. Since it’s so difficult to understand which part of the compressor is not cooperating, it can be better to simply replace the entire thing instead of attempting to fix it.

AC Compressor Clutch, Symptoms Of Failure #3. Halted Clutch

The compressor pulley can disengage or engage from the motor thanks to the clutch. This ensures the part is only operating when it should. If there’s a seizure in the clutch, the normal action is disrupted. Look at the front of the compressor when the AC is running to check whether the clutch is spinning.

AC Compressor Clutch, Symptoms Of Failure #4. Air Won’t Turn On Or Off

Once the clutch breaks, you can’t deactivate the compressor when needed, taking away the power to turn the air conditioning off. This isn’t ideal for other parts of the system and could lead to more severe issues. But, a more common scenario is the clutch breaking and making it impossible to turn the air on instead.

As the clutch isn’t there, the compressor doesn’t get the required power from the engine. Your air conditioning is as good as gone.

AC Compressor Clutch, Symptoms Of Failure #5. Leaking Refrigerant

AC Compressor Clutch

With breakage in the compressor clutch, the bearing inside could get damaged as well. It’s not exactly common; to see fluid seep out of the front deal due to a failed compressor clutch. However, it’s not unheard of either. Inspect the compressor for any signs of refrigerant leakage through the front seal.

AC Compressor Clutch, Symptoms Of Failure #6. Visible Wear and Tear

Like many components of a vehicle, regular wear and tear can take its toll on the AC compressor clutch. Over time, the clutch plate might show signs of corrosion, rust, or even cracks. If you notice any physical signs of deterioration on the clutch, it’s likely that its performance is compromised. Therefore, regularly inspecting the clutch can prevent potential AC problems down the road.

AC Compressor Clutch, Symptoms Of Failure #7. Intermittent Cooling

If your car’s AC occasionally blows cold air and then goes warm intermittently, the clutch could be slipping. A slipping clutch fails to maintain a consistent grip on the compressor pulley, causing fluctuations in cooling. This often results from a worn-out clutch or issues with the clutch’s electrical connections. Addressing this early on can save you from more significant complications later.

AC Compressor Clutch, Symptoms Of Failure #8. Burnt Smell

If you detect a burnt or acrid smell when the AC is running, it’s a warning sign. This smell can arise from the clutch overheating due to excessive slippage. Over time, the friction material on the clutch can wear down and cause slippage, leading to an overheating situation. If left unchecked, this could lead to complete failure of the compressor clutch.

AC Compressor Clutch, Symptoms Of Failure #9. Inconsistent Clutch Movement

While it’s typical for the clutch to engage and disengage in a smooth manner, any erratic or inconsistent movement indicates a problem. The clutch might struggle to fully engage or might engage and disengage rapidly. This can result from electrical problems, a worn clutch, or issues within the compressor itself. An inconsistent clutch won’t effectively cool your car, stressing the importance of timely repairs.

AC Compressor Clutch, Symptoms Of Failure #10. Fuse Blows Repeatedly

The electrical system of a car is interlinked, and the AC system is no exception. If the fuse related to your AC system keeps blowing, the clutch might be drawing more current than usual. This unusual draw can indicate a short or another electrical issue within the clutch mechanism. Replacing fuses without diagnosing the root cause can lead to repeated problems and potential electrical damage.

AC Compressor Clutch, Symptoms Of Failure #11. Vibrations When AC is On

Feeling vibrations in the car, especially when the AC is turned on, can indicate a misaligned or damaged compressor clutch. These vibrations can be felt on the steering wheel, dashboard, or even the car seat. A misaligned clutch can affect the balance of the compressor pulley, leading to these noticeable vibrations. It’s crucial to get this checked out to ensure the safe and efficient functioning of the AC system.

AC Compressor Clutch, Symptoms Of Failure #12. Difficulty Starting the Car

While it might seem unrelated, a failing AC compressor clutch can sometimes make it challenging to start your vehicle. This is because a seized compressor can create a load on the engine, preventing it from turning over efficiently. If you notice difficulty in starting your car, especially when the AC has been running, it’s worth checking the compressor clutch as a potential culprit.

In conclusion, understanding the signs and symptoms of a bad AC compressor clutch can save car owners time, money, and potential discomfort. Regularly monitoring your car’s AC performance and being alert to these signs can ensure that any issues get addressed promptly. Always consult with a professional mechanic if you suspect any problems with your AC compressor clutch.

How To Check AC Compressor Clutch

It shouldn’t take too long to find any problems with your AC compressor clutch. All you need is a few simple tools to complete the inspection.

1. Inspect The Clutch

Get a flashlight and check out the compressor clutch – really get in there! The majority of the time a clutch fails, there will be a burnt or discolored area. The clutch disc operates near flexible rubber isolators. Thanks to those, the disc can move smoothly. When the heat becomes unbearable, the isolators start to melt, giving a rusty color.

If you see these signs in your compressor clutch, you have to replace the whole compressor.

2. Jump Compressor

In case there aren’t obvious signs of a broken compressor clutch, you have to perform further diagnosis. First, unplug the connectors of the compressor and attach jumper connectors to the electromagnet.

You’ll need a wire crimp tool for this as the connectors are tiny. Link the car battery to the wires. One of them should be connected to the negative battery terminal whereas the other route is attached to the positive side.

The compressor clutch will continue kicking if the electromagnet is okay. Take out the positive wires to free the clutch. This process can be repeated several times as needed to ensure the clutch is operational.

Every time the clutch is activated, you should hear a sound letting you know it’s engaged. If this doesn’t go according to plan, there might be a defective magnet on the compressor. You have to get that replaced.

Compressor Clutch Not Engaging

If the AC compressor clutch is not engaging at all, these are the potential reasons and solutions for this:

1. Open Circuit In The System

As mentioned earlier, the AC compressor clutch system relies on an electronic circuit to function. Ideally, it has to work in a closed circuit. If there is an open circuit in the wiring system, the AC compressor clutch won’t engage, and neither will your vehicle’s air conditioning work properly.

These are some of the reasons there may be an open circuit in the compressor clutch system.

Blown Fuse

There is a fuse inside the system that secures it from overloading. If the excessive current passes through the fuse, it breaks and stops the flow of current. As a result, energy wouldn’t reach the compressor clutch and it wouldn’t be able to engage.

Broken Relay In AC Compressor

Apart from a blown fuse, the AC compressor clutch also has a relay. It’s used to protect the switch in the dash panel from large flows of electric current. In a few cases, the coil in the relay snaps and prevents any flow of current through it. Due to this, the battery’s current doesn’t reach the compressor clutch and ultimately, the latter doesn’t engage.

Poor Clutch Coil

If the clutch coil is bad, the AC compressor won’t engage. In most cases, we call a clutch coil bad if the coil inside is broken. This stops the flow of electric current within it so the coil is unable to generate an electromagnetic field. As you can guess, the AC clutch can’t engage without the field.

Bad Grounding

Poor grounding is the final reason behind an open circuit in the compressor clutch. The cable ground can be found near the compressor. Occasionally, it breaks due to corrosion buildup. This can interrupt the flow of electricity and decrease the magnetic power of the compressor clutch.

2. Poor Refrigerant Pressure Switch

The AC system required a refrigerant to turn the heat into cool air. As the compressor engages, the refrigerant is pressurized. There are pressure switches known as refrigerant switches in the system – these control the pressure.

The switches are visible in most cars and can be divided into two categories: high-pressure and low-pressure switches. Generally, the compressor clutch is linked to the low-pressure switch.

If the low-pressure switch starts going bad, the current won’t reach the ground. As a result, the compressor relay doesn’t work or allow the clutch the engage.

3. Inadequate Or Excessive Refrigerant Volume

The final common reason behind an AC compressor clutch not engaging is insufficient or excess refrigerant volume. You only need a fixed refrigerant volume in your car for the AC system to work. Put too much or too little and it would affect the system negatively.

Poor refrigerant volume usually causes the compressor clutch to not engage. Low refrigerant volume impacts the low-pressure switch. Without enough pressure, the switch won’t work. Lastly, it will stop the AC compressor clutch from engaging.

How Long Does An AC Compressor Clutch Last

Now that you’re aware of just how important an AC compressor clutch is for the overall functionality and well-being of your vehicle’s air conditioning system, you should know how to maintain it. The system isn’t everlasting and will require fixes from time to time, but you should know the basic maintenance techniques to keep yours in a good condition.

Something you should know about your car is how long the AC compressor clutch can be expected to last so you can replace it promptly when needed.

Fortunately, the system shouldn’t require replacement very often. Generally speaking, many owners don’t even have to change the compressor clutch during their time with the vehicle. It’s not a very fragile part, to begin with, especially in comparison to other components of the AC system and your vehicle as a whole.

Hopefully, you won’t ever be in a situation where you’re having to bring your car into the mechanic’s shop to get the AC compressor clutch replaced. However, if you do fall into a position like that where you have no other choice, you should be well aware of what you have to do.

AC Compressor Clutch

Can I Drive My Car With A Bad AC Compressor

Let’s say you just got to know that your car has a bad A/C compressor clutch in your car (as you’re learning how to tell if AC compressor is bad). A very responsible driver would rush their vehicle to a professional. Others would be caught up in time or budget restraints. You could be wondering whether you have to fix it right away. Is it something that needs immediate attention, or can you afford to live without it for a while? It depends entirely on a number of variables.

First and foremost, ask yourself if there’s any other way you can keep the interior of your vehicle comfortable without the AC system. People who don’t live in a warm climate can do without an AC. They could simply roll down the windows to cool the car instead of depending on the cool air of the air conditioning.

But you must also consider the car’s AC system’s condition if you decide to keep driving it with the malfunctioning AC compressor clutch. We’ve mentioned before how a bad compressor clutch could cause the drive belt to wear out faster than usual. That could result in overall damage to the AC compressor and you would end up with a costlier repair job on your hands.

Apart from messing with the AC compressor, a poor compressor clutch could lead to issues in the serpentine belt. Again, you would have to replace that sooner than expected. This is why we strongly recommend you replace the AC compressor clutch whenever it shows signs of error.

AC Compressor Clutch Replacement

The average price of an AC compressor clutch is between $800 and $1000. You will have to pay about $150 to $300 worth of labor fees, as well as $450 to $850 for the new compressor. Professionals don’t recommend that you repair the AC compressor clutch. It’s best to install a new one.

As the compressor is an integral part of the air conditioning system, it’s quite pricey. In fact, the price of the compressor is the highest out of all components of the system. But, it’s not hard to replace.

We could call this a no-brainer decision – deciding to replace the AC compressor. However, you shouldn’t rush the decision and simply replace the clutch. Consult with a professional to know whether you need a new compressor or a clutch will do.

There are a few considerations here. Are you planning on keeping your car for another year or two? If yes, then it would be best to invest in replacing the bad compressor clutch. The costs would be well worth it because it will allow you to use the car continuously without problems.

On the other hand, if you don’t think you’ll keep your car for longer, it might not be worth splurging a few hundred dollars on getting the compressor clutch repaired. That’s a lot of money going into a car that won’t be backing up into your driveway for much time.

How To Replace Clutch On AC Compressor

If the AC compressor clutch in your car goes bad, you may be tempted to attempt to fix it yourself. After all, how hard could it be? It’s simply taking the compressor clutch out before popping in a new one to replace it. You could have a fully functional AC system back in no time. Right? Well, not entirely.

If you’re a master in all things car, and we don’t just mean model numbers and specifications – if you’re skilled enough to handle car parts, you could just get away with DIY-ing a fix. But more often than not, this replacement takes a more complicated turn for newbies and they find themselves having to spend much more to get it done right.

There are times when you simply can’t replace the system by yourself. In some cases, you will have to refer to a mechanic or professional to change the car’s system instead of only the compressor clutch. This is because not all AC compressor clutches can be repaired or serviced.

But even if the AC compressor clutch equipped in your car has a green signal for repair, it would be too difficult for you to do – if you don’t have prior experience. Needless to say, most of us aren’t skilled in car parts replacement. You could hurt yourself and harm your AC system when you don’t know what you’re doing. We suggest you leave it to the professionals.

If you’re still not convinced and want to try it for yourself, be our guest. Here’s a guide to help you out.

Who Should Install A New Compressor Clutch

Rather than trying to replace or repair the compressor clutch by yourself (and failing), you could save so much time and effort by bringing it to a mechanic. Or, better yet, take it to a car AC specialist. They will be able to diagnose the exact problem with ease and tell you the best solution.

If they realize that you do, in fact, must have an AC compressor clutch replacement, they may get to work straight up. Plus, the job will be done correctly on the first try. They will also test the system out once they’re done and recharge it if needed.

In Conclusion…

When it comes to the AC compressor clutch, it’s best to not experiment too much by yourself. If you fail to engage the clutch or start it on your own, a mechanic should be the first person you call. Fortunately, this is one of those parts that rarely need replacement so as long as you’re maintaining your car properly, you may not encounter this issue at all.

Frequently Asked Questions

If you’re still curious to learn more about an AC compressor clutch, our FAQs here might help…

How Much Is An AC Compressor For A Car

A brand-new automotive compressor isn’t cheap, unfortunately. For the most part, you could be paying anywhere from $450 to $850 for a brand-new AC compressor, on average. Yet, there are some instances, based on the make and model of your vehicle as well as the mechanic that you’ve entrusted, where it could cost more. In some cases, a brand new HVAC compressor for your car could cost you upward of $1,000, and as high as $1,200 or more. The compressor itself is already pretty expensive, costing as much as $800. Then, you’d have to take into account the labor required to fit it in, which could be between $150 to $200 or higher.

What Is The AC Compressor

The AC compressor in your car, as the name might suggest, is responsible for applying compressive force and pressure. Specifically, it’s the central power unit that makes your car’s AC function the way it does. When the AC unit is running, refrigerant (aka Freon) first travels into the compressor. While doing so, the AC compressor would compress (or pressurize) the refrigerant at high pressures. Then, that highly pressurized refrigerant travels to the condenser. Altogether, the once-gaseous refrigerant (Freon) has now become a liquid. This way, the refrigerant is able to better transfer and exchange heat to cool down your cabin.

How To Test AC Compressor In Car

If your AC unit isn’t blowing out cold air anymore, checking the AC compressor for faults is relatively easy. First, you’ll have to locate where the AC compressor is. Then, turn on the AC unit, and connect a pressure gauge to the low-pressure side of the compressor. Next, grab a Freon recharge kit and add refrigerant into the system to see if the compressor kicks into action. If the reading on the pressure gauge is below around 38psi, you can check the fuses and the rest of the electrical system, such as the AC compressor’s clutches. If all is well, this low pressure alone is indicative that the compressor is faulty.

Will A Bad AC Compressor Affect The Engine

Yes, a bad AC compressor will impact your engine. Granted, its side effects might not be immediately noticeable, but in the long run, you will begin to notice engine-related issues. This is due to the fact that the AC compressor is reliant on power from the engine to run. Should the compressor fail, it would put excess strain on the engine, thus forcing it to work harder. As such, you’ll begin to notice problems like poor fuel economy. Other than that, a bad compressor might, for example, rob power from your engine, hence leaving you with poorer performance and emitting higher emissions as a result.

Where Is The AC Compressor Located

You’ll usually find the AC compressor near the bottom of the engine. Specifically, it should be located right where the drive belt (aka the serpentine belt) is. This is so, as the AC compressor needs power from the engine to operate. You can tell that what you’re looking at is the AC compressor if it has a set of pipes (to carry refrigerant), and an electrical connector to provide current. Oftentimes, the AC compressor is found beneath other accessories that are reliant on the drive/serpentine belt, such as the alternator and power steering pump. If you need to diagnose a bad compressor, it might be easier to reach from the bottom.

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