Gone are the days when an open window was used to cool the interior of your car – now everything is air-conditioned, even in individually adjustable zones. But how does car air conditioning work?
Car air conditioning ceased to be an automotive luxury long ago, but not all systems were created equal. And there is much more to developing your vehicle’s car air conditioning system than you might imagine. But let’s start from the beginning.
The origin of the car air conditioner
In the 1930s, Packard became the first automaker to install an automotive air conditioner called the Weather Conditioner. This was a rather fancy fit option that was done by a supplier once the vehicle rolled off the factory line. That said, it wasn’t a particularly effective system: the condensing unit filled half the trunk, there was no thermostat and if fitted as standard it would have been a costly launch, right after the Great Depression.
At the same time, Chrysler had been busy developing and perfecting its own system launched in 1953. Like the first Packard unit, the Chrysler system also used a trunk-mounted system. It was the Nash Ambassador in 1954 who launched a fully integrated front-end mounted HVAC system. Nash was a joint venture of Kelvinator and its experience in the refrigeration industry has enabled it to produce a better and cheaper system than any other car manufacturer. This system quickly became what you might call the father of the modern car air conditioning system.
Car air conditioning in modern times
Climate control systems have come a long way from their early days with computers, simulations, dyno tests, and field tests used to adapt a car ventilation system. This means that although the ventilation system components are the same from model to model, the ventilation software is unique; some have single, double, and even three-zone systems with dedicated filters and so on.
But how does it actually work? Exactly the same way that the common reverse cycle system works in the home. Simply put, you have a compressor, condenser, expansion valve, receiver, and evaporator. Car air conditioning systems also have a refrigerant which is transformed from gas to liquid by the compressor. Then as it passes through the condenser, fresh air flows through the condenser (think of the small radiator) removing the heat created as a result of switching from high pressure, moving from gas to liquid, then moving through an expansion valve where it becomes a gas again and that therefore, when it enters the evaporator, causes the fresh air that blows through the evaporator to remove the heat (generated when the liquid becomes a gas again) and that the cold air is blown into the passenger compartment.
The car heater works in a similar way and is generally also part of an HVAC unit. Basically, to heat the passenger compartment, the vehicle uses the heat generated by the engine via a radiator that acts as a heat exchanger; hot coolant flows through the “radiator” with a restrictor for warmer air and a fan blows air through the radiator and into the passenger compartment. Obviously, this is a big technical simplification but understanding the process in broad terms helps to know who we are dealing with when it comes to car air conditioning.
Car air conditioning and aerodynamics
Car manufacturers design their vehicles to be as aerodynamic as possible and this also applies to car air conditioning systems, not only to make them fuel efficient but also for the way the air moves through the cockpit, how the temperature changes in different car parts of the same cockpit, the noise of the ventilation system and more. In fact, aerodynamics is not only influenced by the shape of the vehicle but by each of its internal and external components and also by the driving comfort of the driver who drives the vehicle. It goes without saying that nowadays it is impossible to think about driving without car air conditioning!