Car Air Conditioning | How it Works and Problems

Air conditioning is vital in a new car, especially in a country like Spain, where high temperatures are common. The widespread use of it even changed travel habits. Before, people traveled “in the fresh air”, avoiding the central hours of the day. Now, luckily, the temperature no longer affects being able to make a comfortable trip.

It’s not exclusively about comfort. Air conditioning is a safety element. When you drive in the heat, it is easier for fatigue to appear or for you to move more in the seat trying to find a way to cool down, increasing distractions. You also open the windows and insects or dust can get in. And be careful, not only in summer. In winter it defogs the windows much faster by reducing the amount of humidity inside. It also helps eliminate bad odors and purify the air.

The first cars with air conditioning

Being able to “condition” the air in a vehicle’s cabin is a fairly old idea. After searching the Internet we found that in 1884 William Whiteley He did an experiment, placing ice blocks in a container on the roof of a horse-drawn carriage. He then blew the air inward using a fan connected to the shaft. And yes, the temperature dropped because as the air first passed through that frozen area, it cooled down.

A rudimentary system but it was the basis of future innovations such as Wheather Eye of Nash Motors, which (roughly speaking), lowered the temperature of the air by making it pass over water. They implemented it in their cars and also in the later AMCs, in the United States. They developed it in 1938, but it took a while to reach factory models. Contemporary was the system of Hupmobile Evanair-Conditioner another pioneer of fresh air hot water heating systems in the industry.

However, “cooling coils” were available in automobiles Packard for several years before the introduction of these systems. The first car to have air conditioning was the 1940 Packard Super Eight. It was an element that made it stand out from its competition, which is why other American luxury brands, such as Cadillac, soon included it among their accessories.

Air conditioning elements in a car

The air conditioning system is made up of a series of components that work synchronized to ensure that the temperature in the cabin is lower than the outside temperature. It is a closed circuit through which a refrigerant gas circulates that is compressed and decompressed to absorb heat, releasing the cooled air into the passenger compartment and cleaning it of impurities.

These are some of the components of its basic scheme (obviously, there are differences between brands and models):

  • Refrigerant gas: Its great peculiarity is that it can change state without problem to carry out its task. Since January 1, 2018, the R1234yf gas which complies with current anti-pollution regulations and replaced R134a in the automotive industry.
  • Compressor: Increases gas pressure. When you activate the A/C switch in your car it starts to work, powered by the accessory belt.
  • Condenser: This is a radiator located at the front of the vehicle, in front of the engine radiator. It receives the pressurized gas filtered by the dehydrator filter and the change of state from gas to liquid occurs.
  • Dehydrator filter: Located between the compressor and the condenser (in some models it is part of the latter), it is responsible for filtering and drying traces of moisture from the refrigerant gas.
  • Evaporator: It is a radiator of smaller dimensions than the condenser – similar to that of heating –, which cools the air that passes through it and where the refrigerant gas goes from a liquid state to a gaseous state of the refrigerant gas.
  • Expansion valve: Located at the entrance of the evaporator, it sprays the refrigerant liquid inside it. In addition to regulating the passage of refrigerant liquid, it controls the expansion of the high-pressure fluid and prevents it from freezing on the evaporator.
  • Cabin fan: It is the one that introduces the air into the interior of the cabin (its intensity can be regulated, as you surely know).
  • Thermostat: Regulates the temperature inside the cabin (it is located inside the car), either manually or electronically. When the desired temperature is reached, it deactivates the electromagnetic clutch so that the compressor stops working or activates it when it is exceeded.
  • Pressure switches: These are safety elements that, if the pressures are incorrect, cut off the electrical supply to the compressor (hence they are mounted at the inlet and outlet of the compressor).
  • Pipelines: The refrigerant gas circulates through them. If they are at high pressure (about 10-20 bars) they are narrow and if at low pressure they are thicker.

How does air conditioning work in a car?

It seems like magic to press the button and let fresh air come out on a hot day. Actually, there is no trick. The refrigerant gas is compressed and becomes liquid (heating), while when it is decompressed, after being filtered, it cools. These are the steps:

  • An electromagnetic clutch in the compressor compresses the refrigerant gas.
  • The heated gas exits through the expansion valve of the compressor.
  • It then passes through the condenser, where it cools (it reaches a temperature of between 80 and 100 degrees) and becomes liquid (between 50 and 60 degrees) thanks to the drop in temperature produced by the air that enters and that sent by the fans.
  • In this state it is filtered to eliminate impurities and dirt, preventing them from passing to the next part of the air circuit.
  • The refrigerant liquid passes through another expansion valve, which regulates the amount of refrigerant liquid and sprays it towards the evaporator, at a pressure of between 10 and 20 bars.
  • It enters the evaporator, where it returns to a gaseous state (pressure at 2 or 3 bars) and cools the car interior before returning to the compressor.

The process starts there again in a cyclical manner. The energy of the combustion engine itself is used to compress the refrigerant gas, no electricity.

Differences between air conditioning and climate control

Many people confuse air conditioning and air conditioning. Analyzed from a technical point of view they are similar, but they are not identical. Let’s analyze:

  • Air-conditioning: With the wheel to regulate the fan speed, the air conditioning is activated or deactivated. Temperature regulation is manual, but maintaining it during a trip, with different outside temperatures, requires varying it. It is, however, cheaper than an air conditioning system as it has fewer components.
  • Air conditioning: It is capable of mixing cold air and hot air to achieve the correct cabin temperature, without the occupants having to worry about adjusting it. It is more expensive since it incorporates more components, such as temperature sensors outside and inside the cabin, electric motors that move the air intake flaps… and even more so if they differentiate between two, three or more zones, increasing the complexity.

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