Ever wondered how air conditioning works in your car? and how it keeps you cool on those scorching hot days.
Whether it’s the middle of summer or you’re stuck in traffic,
The kind of days when it feels like the sun is just beating down on you, and your car’s interior turns into an oven. You jump in, press the AC button, and within minutes, the air is cool and refreshing.
But it’s not just about a switch and cold air.
There’s a lot of science and engineering packed into that simple action.
How does air conditioning work in your car?
The air conditioning system in your car operates on the principles of thermodynamics and fluid mechanics. It consists of many components working together to cool the air inside your vehicle.
The main function of a vehicle’s AC system is to cool and dehumidify the air inside the vehicle.
Your vehicle’s AC is a heat exchanger moving the heat from the inside of your vehicle to the outside.
To do this, the air conditioning (AC) system uses a substance called refrigerant.
Refrigerants are special chemicals that can change from a gas to a liquid and back again, which is key to the entire process.
Main Components of Your Car’s Air Conditioning System
The main components of the air conditioning system in your car:
- Compressor
- Condenser coil
- Receiver dryer
- Expansion valve, and
- Eaporator coil.
Working
When the AC is turned ON the car’s climate control system sends a signal to engage the AC compressor clutch.
The compressor is connected to the engine’s crankshaft via a belt and is powered by the engine’s mechanical energy.
This contains one or more pistons housed inside cylinders.
As the engine runs, it drives the compressor, which compresses the refrigerant gas.
The refrigerant, initially a low-pressure gas, enters the compressor and gets squeezed into a high-pressure, high-temperature gas.
This hot gas is then pushed into the condenser at the front of the car.
Condenser
The condenser consists of a series of metal tubes and fins, typically made from materials like aluminum or copper, which provide a large surface area for heat exchange.
As the hot refrigerant gas flows through these tubes, it releases heat to the surrounding air.
The air flowing around the twisting tubes of the condenser cools the refrigerant down until it’s a liquid again.
As the refrigerant loses heat, it begins to change from a high-pressure gas to a high-pressure liquid, which is called phase change.
Receiver dryer
As the liquid moves out of the condenser it goes through a little reservoir called receiver dryer.
And this receiver drier contains desiccants.
These desiccants remove any water that’s entered the system so that ice crystals don’t form and damage. Also, the receiver dryer helps separate any remaining gas from the liquid refrigerant, ensuring that only liquid refrigerant flows to the expansion valve
Expansion valve
Here, the system changes from the high-pressure side to the low-pressure side.
The high-pressure liquid refrigerant flows from the receiver-dryer through the expansion valve, where it is allowed to expand. This expansion reduces the pressure on the refrigerant, so it can move into the evaporator.
The liquid refrigerant now turns into a cool mixture of liquid and gas, and it enters the evaporator.
Some vehicles have an orifice tube instead of an expansion valve, but it serves the same purpose in allowing the refrigerant to expand and the pressure to be lowered before the liquid enters the evaporator.
Evaporator
While all the other parts of the system are in the engine compartment, this one is in the vehicle cabin, usually located above the footwell on the passenger side.
The evaporator also has a coil of tubes and fins just like the radiator, but its job is to absorb heat rather than dissipate it.
Refrigerant enters the evaporator coil as a cold, low-pressure liquid, ideally 0 degrees Celsius. The refrigerant doesn’t freeze at this temperature but it does have a very low boiling point.
The heat in the cabin of the vehicle is enough to make the refrigerant in the evaporator boil and become a gas again, just like water turning back to steam.
In gaseous form, refrigerant can absorb a lot of heat. The cooled air is now blown out by the blower fan and circulated into the vehicle’s cabin through the air vents.
Air vents distribute the cooled air throughout the cabin providing a comfortable environment for the occupants.
The refrigerant in gas form enters the compressor, where it is pressurized, and the process starts over again.
The recirculate button and the AC cabin air filter both play a crucial role in ensuring you have clean air and a comfortable environment inside your vehicle.
Here’s how it works
When the recirculate button is off the system draws fresh air from outside which helps to ventilate the cabin and reduce stuffiness. Fresh air is also effective at clearing foggy windows, especially in humid conditions or rainy conditions.
When the recirculate button is turned on, the car’s HVAC system stops drawing air from outside and instead recirculates the air inside the cabin. By reusing the already-cooled air, the AC can cool the cabin faster and more efficiently.
This mode can be used to quickly cool down the cabin or to prevent outside pollutants (e.g., dust, smoke, or fumes) from entering the vehicle. However, it can cause the air to become stale if used for too long without allowing some fresh air in.
Whether the system is using fresh air or recirculated air, the air must be filtered for cleanliness. For this, an air filter is used, located under the dashboard on the passenger side.
When you turn on your car’s AC, the system either draws air from outside or recirculates air from inside the cabin.
Before entering the vehicle cabin, the air passes through the cabin air filter. This filter captures contaminants such as dust, pollen, and other particles, ensuring the air you breathe while driving is cleaner.
How Car Air Conditioning Works in EV
Well, the AC system works a bit differently here.
An electric motor powers the AC compressor in an electric vehicle, rather than a belt connected to the engine.
This motor is driven by the vehicle’s high-voltage battery system.
Electric compressors have fewer moving parts and do not rely on belts which can reduce maintenance needs and improve reliability
In summary, while both IC and EV AC compressors achieve the same goal of cooling the vehicle’s interior
Why Your Car’s AC Might Fail: Common Issues and Solutions
Like any system, the AC needs regular care. If you’ve ever experienced a car AC blowing warm air, there’s a good chance the refrigerant level is low. Over time, the system can leak refrigerant or experience wear and tear on components. That’s why it is important to have your AC system checked and refilled by a professional.
Because automotive air conditioning (AC) systems operate under pressure, they must remain completely sealed from the surrounding environment. Anything that allows refrigerant to leak or contaminants to enter can cause a failure.
If a leak is present in any component, Identify the leak, replace the faulty component, and then evacuate and recharge the system.
Regular maintenance helps ensure that the compressor doesn’t get overworked and that the condenser and evaporator stay clean and efficient.
So that is it about automotive AC system, now let me know what you think about this article. If you have any questions let me know in the comments.
Check out other articles on car air conditioning:
