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Car Compressor: Understanding And Maintaining Your AC System

by Jordan Harris

Have you ever wondered how the AC in your car keeps you cool during the summer and heated up in the winter? Well, let’s discuss all about the AC system and specifically about the main component which is the car compressor.

The air conditioning system in your car works by circulating the refrigerant, converting it from a gas to a liquid, and then back again. At the end of this cycle, it is in a cold gas state inside the evaporator, at which point outside air is blown, cooled, and then sent to the cabin.

This is where the thermodynamic process of maintaining the temperature in the car compartment is involved. Pressure acts here and the internal temperature changes. All you have to do is turn on the air conditioner and the compressor does the rest. However, it’s not as easy as it looks. Let’s dig in and understand how the air conditioning system which includes the compressor functions.

Components Comprising A Car Air Conditioning System

A car air conditioner has almost the same components as a room air conditioner. However, the car is smaller than the room, so many changes have been made to make it compact enough to fit inside your car. The main components used in car AC are:

1. Compressor

The air conditioner compressor is called the heart. Increases the pressure of the refrigerant and converts the vapor refrigerant into a liquid refrigerant. Liquid refrigerant allows air to flow through the condenser.

2. Capacitor

A capacitor is a small device that controls condensation. When adjusting the temperature of the vehicle to low or high, the liquid refrigerant supplied by the compressor must withstand the convective force of the radiator fan or another fan. This force helps control.

3. Expansion Valve

The expansion valve helps high-pressure expansion by sending a cold liquid refrigerant through the condenser. As the name implies, it controls expansion and reduces pressure. The flush pressure before the refrigerant is sent to the evaporator.

4. Evaporator

The evaporator is behind the air conditioner and looks like a heat exchanger. It absorbs the heat of the car and converts it into steam to convert it into a liquid refrigerant. Fans can enjoy air conditioning in the passenger area.

5. Opening Tube

The orifice tube is conical and restricts the flow of refrigerant. This allows the refrigerant to convert the high-pressure liquid refrigerant mist into a low-pressure liquid refrigerant mist before it enters the evaporator.

6. Receiver Dryer

Receiver dryers are known as safety stickers to keep you safe in the car. When using an air conditioner, liquids rather than steam begin to flow into the compressor, which can damage the compressor. Therefore, the receiver dryer is used between the compressor and the evaporator to convert the remaining liquid into vapor and then send it to compression.

7. AC Inline Filter

The air conditioner’s in-line filter kit catches debris and provides clean air.

8. AC Refrigerant

Refrigerants have a low boiling point and are used as heat exchange media for air conditioners. Since it is a liquid, it is very easy to change the temperature. At low temperatures, the refrigerant becomes a gas and at high temperatures, it remains liquid.

9. Accumulator

The accumulator contains a refrigerant. After removing water from the refrigerant bag and drying it, it is circulated in the car.

Note: Car air conditioners use either orifice tubes or expansion valves. The combination of these two is only found in a rear AC system.

Now that you are familiar with all the components of a car AC, you can proceed with the process. We tried to explain step by step how your car AC works.

Working Of A Car Air Conditioning System

All work starts with the compressor. Compresses or pressurizes the refrigerant to convert it from a gaseous state to a liquid state.

The compressed liquid refrigerant then flows through a specific tube inside the condenser. Here, fresh air from the outside comes into contact with the liquid refrigerant. Since the condenser contains a hot liquid, there is a temperature gradient between the liquid and the outside air. The heat is then drawn from the liquid and mixed with the air.

The refrigerant then moves to the receiver dryer or accumulator. The desiccant removes moisture from the air and refrigerant, producing a cooler refrigerant while maintaining the system.

The refrigerant that has already cooled flows into the expansion valve or orifice tube. This process reduces the overall hydraulic pressure and allows it to move to an evaporator (another component of the air conditioning system).

The converted refrigerant then moves to the evaporator. The air from the car is sucked into the evaporator and enters the evaporator core. So far, the temperature of the refrigerant is low and the outside heat can be converted to cold air.

Fans near the passenger seat help cool the car by blowing cold air through the vents. This process also removes moisture from the air and allows you to enjoy fresh and dry air. During this process, the condensate is also collected and drained). After the process, when the liquid refrigerant in the air conditioner becomes hot, it returns to a gaseous state.

At this high temperature, the gaseous low-pressure refrigerant recirculates and returns to the compressor. This is how the new cycle takes place and you can get cool, dry, and fresh air.

Car Compressor

Although a vehicle’s air conditioning (AC) system is made up of many components, the AC compressor serves as one of the central components that create the circuits needed for the system. Without them, the entire air conditioning system would not be able to perform its primary function of creating cold air in the vehicle.

Its main role is to pressurize (compress) the vehicle’s refrigerant to the required pressure, activating heat transfer characteristics and changing the temperature. This creates a cool windshield in the warmer months and a clear windshield in the colder months. In this article, we’ll take a closer look at the role that air conditioning compressors play in vehicle air conditioning systems.

The compressor looks like a pulley attached to a belt-driven engine. This is definitely seen when spending time under the hood.

Car Compressor: Role And Functions

First of all, it is important to understand the relationship between air conditioner compressors and refrigerants. Freon is a commonly used refrigerant and is essentially a type of liquid that converts hot air into cold air (for more insight, check out our guide on how to check freon in car and how to put Freon in car).

This refrigerant and compressor are important duos that work together. Your car’s engine drives an air conditioner compressor with the main task of compressing the refrigerant used to absorb the heated air in your car’s cabin.

As mentioned above, the most commonly used car AC compressor is the swash plate type. The pulley and V-belt drive the compressor. The compressor is mounted on the engine block of the vehicle. When the air conditioner is turned on, the electromagnetic clutch activates the belt drive. The swash plate vibrates the six pistons at both ends, which are responsible for both intake and compression.

Note that the amount of refrigerant flow is controlled by the reed valve. A thin mist of oil then circulates and mixes with the refrigerant to properly lubricate the moving parts.

The air conditioning compressor then draws gas from the refrigerant through the evaporator, reducing the pressure. Decompression causes the refrigerant to vaporize at a low temperature before the AC compressor absorbs and compresses this cold vapor.

During this compression, the refrigerant gas is heated and pushed through the tube into the condenser. Now liquefy it again, generate heat, and then move it to a place to cool. The refrigerant then absorbs heat from the cabin. The evaporator returns to a gas state before it is sucked into the compressor of the air conditioner.

Maintenance Of Your Car AC Compressor

Car AC compressors could collect dust, dirt, dirt, grease, or sand when in the engine compartment. When this happens, the rotating parts of the unit become less efficient and begin to wear prematurely. In this case, the compressor will fail and the air conditioner will not work. Fortunately, the maintenance of the air conditioner compressor is negligible and includes:

  • Using the compressor regularly to properly lubricate all elements of the system.
  • Replenishing the refrigerant to ensure proper air conditioning pressure.
  • If necessary, clean the drive belt and apply tension.
  • Performing electrical checks on switches and sensors, as well as fuses, relays, and coils in EM clutches.

The most common reason for an air conditioner compressor to fail is age-related damage and neglect. If the compressor fails, it will need to be replaced. If you are using a refurbished unit, remember that you will need a recovery machine to protect the atmosphere while recovering the refrigerant.

It is possible to replace certain EM clutches, but keep in mind that, like all engine-powered compressors, some will only be replaced as an assembly.

Air Con Compressor: Potential Issues

There are several issues associated with the air conditioning compressor which might result in total failure of the AC system. The following are some of the most prominent issues among them –

1. Compressor Clutch Problems

The AC compressor has a clutch that is connected to the engine with a belt and pulley, which can also cause problems. The clutch allows you to turn the compressor on and off instead of using it all the time you’re out.

This reduces compressor wear and improves fuel economy by eliminating the need for the engine to rotate the compressor when no cold air needs to be supplied.

2. Electrical Problems

It may sound strange, but electrical problems are the best scenario. AC compressor problems are generally expensive to repair, but electrical problems are trivial in comparison — blown fuses and relays, or loose power plugs.

3. Fuse Failure

A fuse is a clever safety system that prevents serious electrical damage by disconnecting electrical connections. Each electrical module has its own fuse and its exact location depends on the location of the vehicle’s fuse box.

It can be difficult to find around the fuse box and it is easier to look at each fuse. Each can be pulled out for visual inspection or more easily checked using a test light or multimeter.

4. Bad Relay

A car relay is an electromechanical switch that closes the circuit as soon as you press a button or switch on the vehicle. The current flowing through the relay to the electrical system must be routed through the fuse. Relays are also located in the fuse box for simplicity.

Use the figure on the back of the fuse box cover or the instruction manual to identify the AC compressor relay. The easiest way to test this is to turn on the ignition, place your finger on the relay, and activate the AC control switch.

When the electromagnetic force completes the circuit, you will feel the relay move and you will hear a clear clicking sound. If the fuse box is under the hood, ask someone to help you switch the AC control.

Signs Of A Bad AC Compressor In My Car

Car AC Compressor Not Turning On

There are different cases in which your car compressor doesn’t turn on at all; resulting in an extremely hot/cold travel experience. If the air conditioner does not have enough refrigerant, the car compressor will stop working. At that point, it needs to be replenished.

Another problem that could occur is a compressor clutch failure. It can get stuck in the “on” position and the supercharger will always rotate while you drive. Or it may not work altogether. That is, the compressor never turns on. Neither is good. In this case, the clutch may be repairable, but it is recommended to replace the compressor and clutch as one unit.

Car AC Compressor Running But Not Cooling

One sign that there is a problem with the air conditioning system is the relative coldness of the air coming out of the vents inside the car. If you turn on the AC, lower the temperature, raise the fan, and the air coming out of the vents isn’t as cold as it used to be, you might not have imagined it.

It may be an early sign that there is a problem with the air conditioner. The two most likely problems are the loss of refrigerant or the failure of the air conditioning compressor due to a system leak.

Car AC Compressor Whining Noise

When your car makes a strange noise, it’s by no means a good sign, and it certainly applies to air conditioning. As already mentioned, air conditioning compressors do the difficult task of compressing and circulating the air conditioning refrigerant. It is typically turned on and off many times during daily operation and is filled with components that can fail over time.

AC compressors often contain sealed bearings that can wear or seize, especially if the bearing’s lubricant leaks. This can cause a high-pitched squeak and a metal crunch on the metal. When the bearings seize (freeze), the drive belt usually squeaks and the compressor suddenly becomes unable to rotate.

Car AC Compressor Cost

If you want to shop around and to increase the chance of finding the part, it’s miles higher to shop for a brand new AC compressor, in place of a remanufactured or used one.

Car AC Compressor Cost

You can pay a little more for new air conditioner compressors in the $200 to $600 range, but keep in mind that you may have to spend more money after buying a used or readjusted compressor. Obtaining parts directly from a mechanic can save you the trouble of repairing and installing an air conditioning compressor.

Also keep in mind that a remanufactured or used air conditioner compressor could cause a malfunction of the entire car system, not just the air conditioner, and all parts of the air conditioner system may have to be replaced.

Average Car AC Compressor Replacement Cost

In some cases, the AC compressor can be repaired. However, in most cases, it is advisable to replace the defective compressor with a new one. Not only is this the most time-efficient solution to the problem, but in most cases, it leads to better, more permanent repairs.

Labor costs depend on the car you have and can range from $300 to $500. Repair costs for AC compressors can be lower for smaller vehicles that are hard to reach, and for larger vehicles that do not require the removal of some parts when repairing the air conditioner compressor.

Average Car AC Compressor Replacement Cost

The price also depends on the amount the mechanic charges per hour. If it is a dealer, the price will always be higher, and if you go to a specialist, the cost can be higher than a regular mechanic.

There are many factors that can affect the cost of repairing an air conditioner compressor. As already mentioned, one of them is time. The time frame depends on where the part is, how easy or difficult it is to obtain the part and the speed of the mechanic.

Vehicle AC Compressor Facts:

  1. A car’s AC compressor is responsible for pumping refrigerant through the AC system to provide cool air in the cabin.
  2. Low refrigerant levels and failing AC compressors are the most common causes of a malfunctioning AC system.
  3. Poor air conditioning performance, such as warmer air coming from the vents, is a clear sign of a compressor issue.
  4. It can be difficult to distinguish between AC compressor problems and low refrigerant levels since they work together.
  5. Optimal freon levels but poor AC performance is a sign of AC compressor failure.
  6. Inconsistent AC performance, working well one day and poorly the next, is another symptom of a failing AC compressor.
  7. Sudden drops in AC performance tend to indicate compressor failure.
  8. Unusual noises from the AC system can also point to a compressor problem.
  9. Diagnosing AC problems, especially with the compressor, can be complicated and fragile, requiring professional insight.
  10. A mechanic can diagnose the root cause of AC troubles and develop a repair plan to restore your car’s cooling system.

Car AC Compressor Conclusion

This article has covered quite a bit about the air conditioning system, especially the compressor. First, you learned the basics of a car air conditioning system and its functioning. Next, we focused on the potential issues and maintenance.

After learning about the problems and their symptoms we discussed the repair costs and labor charges. Now I believe you will be able to maintain your AC system effectively and save yourself from the heat.

F.A.Qs On Car AC Compressor

Here are some popular FAQs:

How To Quiet A Noisy Car AC Compressor

Turn off the air conditioner for easy access to the fixing process. Remove broken air conditioner parts such as condensers, compressors, and air filters and repair new silent features. However, it is in your greatest interest to take your car to a trusted mechanic who can properly diagnose and correct the true cause before further damaging your car.

How To Tell If Car AC Compressor Is Bad

You may hear strange noises when you turn on the air conditioner in your car. Hot air blowing through the vents while you expect cold air is another significant symptom of a bad compressor.

How Much Is An AC Compressor For A Car

The cost is highly dependent on the year the vehicle is manufactured. However,  air compressor replacement and labor costs typically range from about $900 to $1,500.

How Much To Fix AC Compressor In Car

The cost of car repairs and automatic air conditioner compressor repairs is calculated based on the cost of the parts and the hourly wage multiplied by the time it takes to work. Some car owners want to buy parts from car junkyards and recycled parts. It’s important to remember that all of these parts are already worn and may need replacement sooner than expected.

How To Test Car AC Compressor

Turn on the vehicle, put it in park mode (for automatic transmissions), and apply emergency braking. Turn on the air conditioner. Connect the pressure gauge to the low-pressure side of the AC compressor. Add about 2 ounces. Use Freon to see if the compressor works (if it does, you will hear a loud click and then a stuttering sound).

How Much To Replace AC Compressor In Car

Replacing a car compressor costs an average of $900. The average price of a car air conditioner compressor in the United States in 2022 ranges from $850 for a single compressor to $1200.

How To Recharge Car AC After Compressor Replacement

After you’ve finished replacing your car compressor, you`ll need to evacuate the AC system and recharge it. To do this, you will need a vacuum pump and a set of AC gauges. You should make sure you have the correct amount of refrigerant with you.

How Often Should A Car AC Compressor Cycle On And Off

A standard car air conditioner turns on and off about 2 to 3 times an hour or about 15 to 20 minutes. It helps it to function properly and cool the air inside the cabin.

How To Test Car AC Compressor With Multimeter

Check for energy and ground with the AC compressor clutch, and find out why the compressor clutch has no power. Make sure there’s no ground at the relay coil and then check the continuity at the pressure switch.

Where Is The AC Compressor Located In A Car

It’s usually found at the front of the engine and is belt-driven from the crankshaft pulley. Follow the AC hose to find it. In the case of an electric vehicle, it is driven by an electric motor like a refrigerator at home. So the compressor can be installed almost anywhere. Again, follow the hose to find it.

What Does A Compressor Do In A Car

Your car’s compressor pumps the refrigerant through your air conditioning system, providing cool and comfortable air to your car. Without this circulation of refrigerant, the air circulating inside the cabin cannot be cooled, resulting in an air conditioning system that produces warm air.

Can I Drive My Car With A Bad AC Compressor

You can definitely ride it with a bad air compressor because a faulty compressor is just a pulley. The motor is not dragged and there is no drag to cause excessive friction. Don’t worry about the air conditioner, don’t need it, can’t afford to repair it right now. Just make sure the accessory belt is tight and the compressor wheel is not shaking unbalanced.

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