What Is A Car AC System? Parts, Diagram And How It Work

Automobiles are designed with an air conditioning system to keep users comfortable by cooling the car interior in hot weather. Modern vehicles also control cold weather by using heat from the engine.

The Packard Motor Company first introduced the AC system in the United States in 1939, and it is now a standard feature in all vehicles for the convenience of people.

A vehicle’s air conditioning system works by using a refrigerant gas and compressor to cool the air in the cabin. This compressor is connected to an evaporator that cools the air as it passes through.

The cooled air is then distributed through the vents in the car cabin. Well, in this reading, we’ll learn what a car air conditioning system is, its diagram, parts, types and how it works. We’ll also learn its symptoms of failure.

Let’s get started!

What Is A Car Air Conditioning  System?

A car air conditioning system is a set of components that work together to cool the vehicle’s interior. It functions similarly to the AC systems used in homes and offices.

The system does not actually create cold air but rather cools the surroundings to provide comfort, using components such as a compressor, condenser, and evaporator. Cars use two types of air conditioning systems, which include an expansion valve system that lowers the refrigerant pressure, and the other uses an orifice tube.

Diagram Of A Car AC System

Car AC System

Parts Of A Car AC System

A car’s air conditioning (AC) system consists of several key components that work together to cool the interior of the vehicle. Here are the main parts:

Compressor

The compressor is one of the major components in the air conditioning system. Its functions include pressurizing the refrigerant to cool the air, sensing temperature changes inside and outside the car, monitoring and controlling temperature output, and finally moving air to the condenser. 

Condenser

The condenser in the car’s air conditioning system is located at the front of the radiator. It has been named a mini-radiator because it looks like a radiator. As the compressor pressesurizes the refrigerant, it cools and compresses the hot gases that escape from the system.

Another function of a condenser is to transfer cooled liquid refrigerant to the receiver, dryer, or accumulator. 

Receiver, Dryer, or Accumulator

Vehicles use either a receiver or an accumulator based on their model. The receiver is used in vehicles with a thermal expansion valve, while an accumulator is used in vehicles with an orifice tube.

The receiver separates gas from liquid to prevent liquid from entering the compressor. Compressors are designed to handle gas, as liquid can cause contaminants, but filters help protect the system. Compressors also remove moisture using desiccant.

Thermal Expansion Valve or Orifice Tube

The thermal expansion valve, or orifice tube, is located between the condenser and the evaporator. The thermal expansion valve uses a receiver or dryer, while vehicles with orifice tubes utilize an accumulator. The purpose of the car cooling system is to monitor the amount of pressure and temperature in the system.

Evaporator

The evaporator, located behind the dashboard, cools the air with refrigerant before it is blown into the vehicle’s cabin. The system works by circulating refrigerant through a closed-loop system, changing it from gas to liquid and back to gas.

The car engine powers the compressor, which converts low-pressure gas into high-pressure before sending it to the condenser to release heat and cool the gas.

Related: What Is A Cooling System? Its Diagram and How It Works

Types Of Car Air Conditioning System

Today’s automotive industry uses two main types of AC systems in a car. What makes each system unique is the kind of device that lowers the refrigerant pressure. The following are its two main types:

Expansion Valve System

Among automotive air conditioning systems, the expansion valve system is the most often used. It controls the refrigerant flow to the evaporator with an expansion valve. The expansion valve keeps the refrigerant flowing at a steady pace, which helps to keep the car’s interior temperature stable.

Advantages

Disadvantages

  • Improved cooling efficiency
  • Increased compressor lifespan
  • More accurate temperature regulation
  • It costs more than the fixed-orifice tube system.
  • Needs more upkeep

Fixed Orifice Tube System

A less complicated type of car AC system is the fixed orifice tube system. It controls the flow of refrigerant to the evaporator using a fixed orificetube. By limiting the refrigerant flow, the fixed orifice tube helps to keep the car’s interior temperature stable.

Advantages

Disadvantages

  • A more cost-effective alternative to the expansion valve method
  • Little maintenance is needed.
  • Temperature regulation is less precise.
  • Car cooling efficiency is lower.
  • Less compressor life.

How A Car Air Conditioning System Works

When the air conditioner is turned on, the compressor compresses the refrigerant in the system, which causes the pressure and temperature of the refrigerant to increase. As the refrigerant passes through the condenser, it loses heat.

It then goes through the receiver/dryer to eliminate moisture and impurities. It then proceeds to the expansion valve. As it flows into the evaporator, the refrigerant undergoes a process of cooling as it loses pressure and heat. The dashboard’s evaporator functions similarly to a little radiator.

Air is forced through the chilled evaporator, which cools and eliminates moisture from the air. That cool, dry air enters the passenger compartment via vents. For you to enjoy that cool, refreshing air, your air conditioning system has to work hard.

Symptoms Of A Bad AC System In A Car

If your car’s air conditioning system is not functioning properly, you may notice several symptoms. Here are some common signs of a bad AC system:

Weak Airflow

There are numerous causes of the weak airflow that drivers experience over time in their vehicles. This symptom could damage or cause fatal damage to the A/C system. Below are the causes of weak airflow:

  • A fried ventilation fan is a cause of weak airflow. This is when the fan in the system is not blowing, causing air to not flow effectively.
  • There could be mold accumulating in the evaporator core from residual moisture. 
  • Hose loss is the root cause of poor airflow in automobile air conditioning systems.
  • The core case that houses the blower has seals that can open up. This will also diminish the airflow in the system. 

Reduced A/C System Functionality

There could be a number of causes for your A/C to occasionally lack essential coolness. When the symptom occurs, it should be fixed as soon as possible, or else big damage will be caused to the system. Below are the causes of these symptoms. 

  • A failed blower motor or blower resistor.
  • If there is a clog that expands the tube or refrigerant charging hose,
  • When electrical parts like a fuse, switch, relay, solenoid, or control module fail, symptoms occur. 
  • A damaged or failing condenser or evaporator is also a major cause. 
  • Leak vacuum 
  • A failed compressor or compressor clutch can also cause a weak system. 
  • A failing o-ring seal or component is the root cause of a freon leak.

A/C Cools First But Warms Shortly

Numerous problems are to blame, but you should look into and address them to keep the system functioning normally. A DIYer won’t be able to fix the issue; otherwise, the whole system will be scattered. Below are the common causes of such a problem: 

  • A clogged expansion valve is a major cause of this problem. 
  • A faulty compressor clutch is also a major cause of such an issue. 
  • The fuse that powers the A/C system can shoot out and cause the system to stop working. 

A/C Vents Smelling Like Gym Lockers

Instead of experiencing cool air from the vent, the order from the gym locker takes charge, which is not cool. Below are the common causes of the issue: 

  • A moldy evaporator case is a common cause.
  • Old and dirty cabin filters are another potential cause.
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