AC Compressor Clutch

AC Compressor Clutch: Everything A Car Owner Should Know

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 an 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, 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. Keep reading to know more. Refer to this guide to jump any section you’re specifically interested in.

What Is an 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 your 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.

How Does an AC Compressor Clutch Function?

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.

AC Compressor Clutch Location

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.

Signs of a Malfunctioning AC Compressor Clutch

As the 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.

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.

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 to 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.

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.

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.

Leaking Refrigerant

With breakage in the compressor clutch, the bearing inside could get damaged as well. It’s not exactly common; seeing 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 leakage through the front seal.

Diagnosing Possible Problems

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.

Inspect the Clutch

Get a flashlight and check out the compressor clutch – really get in there! The majority of the times 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.

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.

Why is the AC Compressor Clutch Not Engaging?

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

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 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 later 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

A poor grounding is a 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.

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.

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.

The Lifespan of an AC Compressor Clutch

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 in a position like that where you have no other choice, you should be well aware of what you have to do.

Can You Drive with a Bad AC Compressor Clutch?

Let’s say you just got to know that your car has a bad AC compressor clutch. 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 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 Cost

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.

Is the Price Worth It?

There are 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.

Can You Replace a Bad Compressor Clutch on Your Own?

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 for yourself, be our guest. Here’s a guide to help you out.

Who Should Install a New Compressor Clutch in Your Car?

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.

AC Compressor Clutch – Bottom Line

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.

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