The Basics of Car Air Conditioning Systems

In this modern age, we drive our vehicles to and from work, school, and everywhere else, basking in the comfort that our car air conditioning system provides (especially during the summer months).

With a simple slide of a lever, push of a button, or turn of a dial, we can effortlessly switch from very hot to super cold in mere seconds without regard as to how our car air conditioning unit functions. That is, of course, until the day that it breaks and we suddenly find ourselves roasting (or freezing) in our own car.

The Complexity of Today’s Car Air Conditioning Systems

Ever since car air conditioning systems became widely popular in the 1940s, the technology behind it has also gone through a lot of modifications and enhancements. The complexity car air conditioning systems have become even more complex over the years through upgrades to the general durability, as well as computerized automatic temperature controls.

It has gotten to the point where it is virtually impossible for the average person to perform DIY (Do It Yourself) repairs on them when they break down. When it comes to car air conditioning repairs, we turn to our trusted, qualified mechanics. However, what everyone CAN do is to learn the basic inner workings of car air conditioning systems.

The Basics of Car Air Conditioning Systems

Understanding the basics of car air conditioning systems will help car owners in a number of ways.

For example, some car owners get worried whenever they see anything dripping from underneath their vehicle. However, if you know that typical air conditioning systems generate water, then you’ll know that it is perfectly normal to see water dripping from under your vehicle.

We have divided the basics of car air conditioning systems into two main topics:
1) How Does a Car Air Conditioning System Work? – Explaining how evaporation, condensation, compression, and expansion happen in an air conditioner.
2) Car Air Conditioning Components – While air conditioning components may vary from vehicle to vehicle, the most common components include the compressor, condenser, evaporator, orifice tube, thermal expansion valve (TXV), receiver-dryer, and the accumulator. (Click here to skip to that section)

How Does a Car Air Conditioning System Work?

As suggested by its name, a car air conditioner “conditions” the air by cooling it down and decreasing humidity or moisture content. Your vehicle’s air conditioning system function based on two primary principles which are evaporation and condensation, succeeded by two other stages, the compression and the expansion stages.

  1. Evaporation – a kind of liquid vaporization that happens solely on the liquid’s surface.
  2. Condensation – this is the complete opposite of evaporation and is defined as the transformation of matter from gas to liquid.
  3. Heat of Compression – to illustrate more clearly, let’s use a bike pump as an example. When air is pumped into the bike’s tires, the air will be compressed and the air molecules will be bonded even closer together which will then lead to giving off heat because of friction.
  4. Expansion – this can be defined as matter’s natural tendency to alter its form as a response to a change in temperature, which in the case of car air conditioning systems involves matter being transformed from a liquid refrigerant to vapor.

Car Air Conditioning Components

  • Compressor – also known as the heart of the air conditioning system, it is a pump that is belt-driven and attached to the car engine. Its main task is to compress and transfer the refrigerant gas.
  • Condenser – the area where heat dissipation happens. In most systems, condensers may look like the car’s radiator since they have the same purpose and that is to radiate the heat.
  • Evaporator – this primarily functions to absorb heat but is also used for dehumidification. When warm air passes via the cooler evaporator coil’s aluminum fins, the air’s moisture, as well as any pollen and dust will condense on its surface.
  • Thermal Expansion Valve or TXV – regulates the refrigerant flow going into the evaporator and found in most aftermarket and import air conditioning systems. It is also able to detect both pressure and temperature.
  • Orifice Tube – functions like the thermal expansion valve and found in plenty of Ford and GM models.
  • Receiver-dryer – used on car air conditioning systems with a thermal expansion valve and needs a liquid refrigerant. This is utilized to make certain that the TXV gets the liquid refrigerant, with its main function being the separation of liquid and gas. It likewise functions to filter dirt and eliminate moisture. Normally, it makes use of a sight glass found on its top portion for charging the system.
  • Accumulator – used on air conditioning systems with an orifice tube and like a receiver-dryer, meters refrigerants coming into the evaporator. It stores the surplus liquid refrigerant and is directly attached to the evaporator. Like the receiver-dryer, it separates liquid and gas since liquid can damage the compressor. It can likewise eliminate moisture and debris.

Note: If your car air conditioning unit has an accumulator; it will not have a receiver-dryer since these two components function in the same way. Also, your car will either have an orifice tube or a thermal expansion valve (TXV). It won’t have both components.

There are plenty of things that can go wrong in the complex car air conditioning system. Specialized equipment is usually vital to being able to determine the causes of common car air conditioning problems. If you are having a problem with your car air conditioning unit, you should have a qualified professional diagnose and fix the problem.

Additional Resources for Car Air Conditioning: