How Can You Tell If an AC Compressor Is Bad?
Whether you’re looking at your car’s AC or the AC in your home, air conditioning units work in similar, but different ways. So it isn’t always easy to figure out what’s acting up. There are all sorts of problems that cheap air conditioners—and even expensive units—can run into. With a little research, though, you can be well on your way to making the right repairs!
What Are the Symptoms of a Bad AC Compressor?
The signs of a bad compressor in your car will typically be the same as the AC compressor issues for your home unit. For starters, you’ll notice that you aren’t getting cold air coming from the vents. Having a broken AC means there’s no way to keep cool, so you’ll be experiencing an increased temperature around the house or higher engine temperatures in your car, too.
Another problem could be loud or unusual noises coming from your engine or AC unit. One of the sure signs of a bad AC compressor bearing is a high-pitched squealing or grinding sound. That type of bad AC compressor symptoms noise will definitely get your attention.
Then again, you might have a compressor clutch that isn’t moving. In your car, when the AC compressor clutch is engaged, you should be able to look at the engine and see the inner portion moving. Home AC systems do not have a clutch, but you might still see signs of a bad AC compressor bearing if there are leaks around the compressor. The most common leaks around an AC compressor are refrigerant leaks, and when that happens, you’ll know it’s time to make some repairs. But before jumping into repairs, you might wonder, Is replacing an AC compressor difficult? The answer depends on your experience and comfort level with mechanical and electrical systems. Replacing a compressor, whether in a car or a home unit, often involves removing multiple components and handling refrigerant, which requires specialized tools and knowledge. Because of these challenges, it’s usually best to consult a professional unless you have the necessary expertise. Mistakes during replacement could lead to further damage or safety hazards.
How Do I Test My AC Compressor?
In general, the first thing for how to check if your car AC compressor is working would be to feel for any cool air from the vents. If there’s no cool air, then the air conditioning is out. More specifically, there might be something wrong with the AC compressor. One of the signs of a bad compressor in your car has to do with the compressor clutch, so it’s a good idea to take a closer look there.
When you’ve already looked for refrigerant leaks and listened for unusual sounds, it might be time to get out a multimeter to check the electrical voltage. This tool can work for both your car’s AC compressor and your home’s AC unit. Ensure the power is completely turned off, then use a multimeter set to the capacitance setting to check the capacitor by comparing the reading to the capacitor’s rated value. If it’s significantly off, the capacitor may be faulty, which could cause the compressor not to start. The reading between the Start and Run resistance should be the sum of the resistances for the Common and Start and the Common and Run. If it’s not adding up correctly, that could be a sign of a bad compressor in your car or indicate that the AC unit compressor windings need to be corrected.
You can also use the multimeter to check for ground fault. There should be no continuity, so if there is continuity, that indicates a ground fault. In this case, the compressor may need to be replaced altogether.
How Do You Tell If an AC Compressor Is Bad or Just the Clutch?
The AC compressor in a car is driven by the engine via a belt, and it has a clutch that engages and disengages to turn the compressor on and off as needed. This helps manage the load on the engine and improve fuel efficiency. But like any mechanical part, it won’t last forever.
You can inspect the compressor clutch on your car by first locating the AC compressor under the hood. It’s typically found at the front of the engine bay, connected to the serpentine belt. From there, you can inspect the compressor clutch and pulley for any visible signs of damage, such as cracks, excessive cracks or debris. The belt needs to be in good condition and properly tensioned to get your air conditioning to run correctly.
It’s sometimes helpful to manually engage the clutch to check if the car AC compressor is working. With the engine off, you can try to manually rotate the clutch plate. It should turn freely without excessive resistance. Otherwise, you might be looking at one of the classic bad AC compressor clutch symptoms. If it’s hard to turn or stuck, the clutch or compressor might be faulty and need replacing.
How Do You Know If Your AC Compressor Needs to Be Replaced?
You can usually tell that your home AC compressor will need to be replaced if you notice that the unit only blows warm air instead of cold, or if the compressor makes unusual noises, like grinding or clanking. Then again, you might also be dealing with frequent tripping with the circuit breakers, or have a compressor that fails to start at all. Visible refrigerant leaks or oil around the compressor can also signal that it’s time for replacement.
In a car, the question is a little different. Those bad AC compressor clutch symptoms you’ve been noticing might lead to bigger problems. A broken air conditioner at home is only responsible for one thing: cooling your home. But how will a bad AC compressor affect the engine on your car while you’re driving around town or on the interstate?
If the compressor seizes and it's driven by the same belt that drives essential components like the alternator or power steering pump, it can cause the belt to break. This can lead to a sudden loss of power steering, alternator function, and potentially engine overheating. Then again, every vehicle is different, and how long you can drive with a bad AC compressor depends on the make and model of your car.
If the AC compressor is making noise or not cooling properly or you’re getting other bad AC compressor clutch symptoms but they aren’t affecting other systems, you can technically drive indefinitely without using the AC. The AC system isn’t essential for the vehicle's operation, but knowing how will a bad AC compressor affect the engine is still critical. A failing compressor can spread debris through the AC system, leading to more extensive and expensive repairs.
Ultimately, the safest approach is to address the issue promptly so you can avoid any unexpected breakdowns. The same goes for your home air conditioning unit. If you can replace your AC compressor and get back to keeping cool, then why wait?
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