What are the Four Major Components of Air Conditioning?

There are four major components of the air conditioning system. They are the evaporator, condenser, compressor, and expansion valve. Each of these air conditioner components functions in sync with each other and has a specific job to do, to keep your air conditioner running smoothly.

1. Evaporator coils

The evaporator coil is the component in your AC system that absorbs the heat from the air inside your home. It is often either attached to your furnace or located on the inside of your air handler. It works with a condenser coil to complete the heat exchange process that produces cool air. Evaporator is an important component together with other major components in a refrigeration system such as compressor, condenser and expansion device. The reason for refrigeration is to remove heat from air, water or other substance. It is here that the liquid refrigerant is expanded and evaporated. It acts as a heat exchanger that transfers heat from the substance being cooled to a boiling temperature.

2. Compressor

Perhaps the most important of all air conditioner components, the compressor is the workhorse of air conditioning. For central and split systems, the compressor is located in the outdoor unit. The majority of an air conditioner’s energy consumption is because of the compressor, and it is generally the most expensive part of the system. The purpose of the compressor is, as the name suggests, to compress the refrigerant, which is a warm vapor as it reached the compressor, to a hot compressed liquid. As the air conditioning process continues, this is then cooled down and expanded again to remove heat from the indoor air. More on this later in the article. Based on the size of your air conditioner, the size of the compressor will vary. You can keep the most important AC component healthy by often checking for refrigerant leaks, preventing dirt & contamination, keeping the condenser coils cleaned, and keeping your AC well oiled.

3. Condenser

A condenser (or AC condenser) is the outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year. Both split air conditioner and heat pump condensers are made of the same basic parts. The condenser cabinet contains the condenser coil, a compressor, a fan, and various controls. The condenser coil can be made of copper tubing with aluminum fins or all-aluminum tubing so heat can be rapidly transferred. The condenser fan is a vital component and circulates the air across the coil to facilitate heat transfer. The compressor is the heart of the system since it compresses the refrigerant and pumps it to a coil in the form of a hot gas. In air conditioners, the refrigerant is cooled at the condenser into a warm liquid, and passes through a pipe into the evaporator coil where it expands and cools. In heat pumps, the hot gas is pumped directly to the evaporator coil to provide heat.

4. Expansion Valve

Expansion valves are devices used to control the refrigerant flow in a refrigeration system. They help to facilitate the change of higher pressure of liquid refrigerant in the condensing unit to lower pressure gas refrigerant in the evaporator. The term “low side” is used to indicate the part of the system that operates under low pressure, in this case the evaporator. The “high side” is used to indicate the part of the system that operates under high pressure, in this case the condenser.

Types of Expansion Valves

There are basically four types of valves that are in use. These valves are also referred to as metering devices.

Automatic Expansion Valve: It regulates the flow of refrigerant from the liquid line to the evaporator by using a pressure-actuated diaphragm. It maintains a constant pressure in the evaporator.

The setback is that it is not efficient if the load fluctuates hence this type is not suitable for use in air conditioning as the load fluctuates a lot during its operation.

Thermostatic Expansion Valve : It uses a valve mechanism to control the flow of liquid refrigerant into the evaporator coil. The flow is controlled by the pressure in the evaporator.

This type of metering device is able to operate well when the load fluctuates and hence is suitable for use in air conditioning systems. When the evaporator warms, the valve provides a higher flow rate and when it cools, it reduces the flow rate.
It is also commonly referred to as the TXV, TEV or TX valve. There is a sensing bulb which detects the temperature of the coil and is usually located at a higher temperature within the evaporator.

The bulb must be clamped firmly to the coil to ensure proper sensing. When the temperature of the evaporator increases due to the demand for cooling, the pressure in the bulb will also increase hence pushing the spring to open the valve.
Similarly, when the temperature of the evaporator reduces due to a lack of demand for cooling, the pressure in the bulb will drop hence causing the spring to close the valve.

Capillary Tube: It is a tube with small internal diameter and could be coiled for part of its length. It is installed to the suction line. A filter-drier is sometimes fitted before the tube to remove dirt or moisture from the refrigerant.

Float valve: It is actuated by a float that is immersed in the liquid refrigerant. Both low-side float and high side-float are used to control the flow of liquid refrigerant.
The low-side float helps to maintain a constant level of liquid refrigerant in the evaporator. It opens when there is no liquid in the evaporator and closes when there is liquid in the evaporator.

What are the Four Major Components of Air Conditioning?