Understanding Your Car’s Air Conditioning: More Than Just Cooling says Kiran Parmar
As the first major heatwave hits UK, we thought now is a good time for Free Car Mag to investigate the cooling miracle of automotive air-conditioning!
When the summer sun blasts down on planet Earth, few inventions provide as much relief as your car’s air-conditioning. While we often think of it as a seasonal luxury, your vehicle’s climate control system is a complex piece of engineering designed for year-round comfort and safety.
How It Works: The Science of Phase Change
At its core, car air-conditioning relies on the principle of phase change— the process of turning a liquid into a gas to absorb heat. The system is a closed loop filled with refrigerant.
Compression: The process begins at the compressor, powered by the engine. It squeezes the gaseous refrigerant, raising its temperature and pressure.
Condensation: This hot, high-pressure gas moves to the condenser (usually located at the front of the car), where it releases heat to the outside air, turning back into a high-pressure liquid.
Expansion: The liquid passes through an expansion valve or orifice tube. As it moves into a low-pressure area, it rapidly expands and turns into a cold, low-pressure liquid/gas mixture.
Evaporation: This cold mixture enters the evaporator, located behind your dashboard. As air from the cabin passes over the cold coils, the refrigerant absorbs the cabin’s heat, cooling the air before it blows into your car. The refrigerant then returns to the compressor to repeat the cycle.
A History of Cool: The First Systems
The concept of automotive air-conditioning dates back further than many realise. Packard holds the distinction of being the first car manufacturer to offer a factory-installed air conditioning system, introduced in the 1939 Packard.
The system, marketed as “Weather-Conditioned,” was pioneering but cumbersome. It lacked a thermostat or an off-switch—to turn it off, you had to stop the car and manually remove a belt from the compressor. Despite the innovation, it didn’t immediately take off due to the high cost and the fact that the evaporator took up nearly half of the car’s boot space.
Why Use It All Year Round?
Many drivers believe air-conditioning is only for hot days, but it serves a vital function in winter: dehumidification.
The system doesn’t just cool air; it removes moisture. In damp or cold weather, running the air conditioning—even with the heat turned up—is the fastest way to clear a foggy windscreen. By pulling humidity out of the interior air, you prevent condensation from forming on the glass, ensuring optimal visibility and safety. Additionally, using the system regularly keeps the internal seals lubricated. If left dormant for months, the refrigerant can leak, and the seals can dry out, leading to expensive repairs when you eventually try to turn it on during the first heatwave of the year.
What should I do on a really hot day?
On a very hot day, open your windows as soon as you get into your car or better still, press and hold the unlock button on your key fob to open the windows before getting in (if your car has this feature), then drive for a few minutes with the windows down. This will allow the hot air inside your cabin to escape rapidly, then switch on you’re A/C to the coldest setting using a medium to high fan speed to further cool your vehicle’s interior to a comfortable temperature. If you press the recirculation button, your system traps and continuously chills the cool air already inside rather than constantly cooling hot air pulled from outside.
You can also use the recirculation button to prevent foul odours such as diesel fumes, smog, burning smoke, fire smells etc from entering your cabin. On a long drive switch it periodically to fresh air to stop build-up of exhaled CO2. Some modern cars with sophisticated climate control systems will automatically detect when outside air quality is poor and automatically switch to recirculation mode, you can even adjust the sensitivity of this feature by going into ‘Car systems’ then ‘AC’ some models. Also check the footwell temperature is set to cool during the summer months and change it back to warm at the start of winter.
If you own a modern car such as our Audi A6 c7, you will have to go into the MMI system and set the air-conditioning to ‘Intensive’ mode for the most powerful level of cooling. Also check that the front and rear temperatures are ‘synced’ together as there is no point the rear vents blowing hot air whilst you the driver at the front are trying to cool down the entire cabin to a comfortable level.
Maintaining Your System
To keep your cool, follow these simple maintenance habits:
Run it at least monthly: Regardless of the season, turn your air conditioning on for at least 10–15 minutes once every two weeks. This keeps the oil circulating and prevents seals from cracking, better still – keep the A/C active all year round.
Replace the cabin air filter: Located behind your glovebox or under the hood, this filter traps pollen, dust, and debris. If it gets clogged, it restricts airflow, forcing the system to work harder. Replace it according to your owner’s manual (usually every 12,000–15,000 miles).
Watch for signs of failure: If you notice a musty smell (often caused by mould buildup on the evaporator) or if the air isn’t as cold as it used to be, have it checked by a professional, the system may have to be re-gassed.
Professional servicing: Every two to three years, have a technician check the refrigerant levels and system pressure to ensure everything is operating at peak efficiency.
Normfest Products: Use products such as ‘Normfest Viro Fresh Plus’ and ‘Viro Dry Shot’ to clean, disinfect and sanitise, your entire air-con system leaving a fresh and pleasant scent inside your cabin.
By understanding the mechanics behind the breeze, you can better appreciate this essential system and ensure it remains a reliable companion on the road, no matter the weather. Happy summer motoring everyone!
