The above diagram illustrates a typical vehicle air conditioning system layout.
How it Works!
Air Conditioning (A/C) systems are becoming more and more complex with the ever increasing advances in technology. So, in an attempt to keep things fairly simple for the average vehicle technician, enthusiast or the genuinely interested, we will take a look at a typical air conditioning system by taking each of the main components in-turn and describe their location and function within the A/C system.
1 - The Compressor
Let's begin with the heart of the system, the compressor. There are a number of different types of compressor currently used in modern vehicles including piston, rotary vane, scroll wobble plate, magnetic clutch and even clutchless. Despite this, all these compressors have a common purpose - which is threefold:
Firstly, the compressor must transfer refrigerant (for the cooling effect) and oil (for the lubrication of component parts) around the system. Secondly, the compressor must increase the pressure (and thus the temperature) of the refrigerant before it enters the condenser. And thirdly, the compressor must draw low pressure refrigerant from the evaporator in order to repeat the cycle.
The compressor is located at the front left or front right of the engine where its pulley is driven by the auxillary drive belt. It draws cool refrigerant vapour from the 'low pressure' lines and compresses it into 'hot - high pressure' vapour for delivery to the condenser.
2 - The Condenser
The condenser is located at the front of the engine compartment (in front of the radiator) and receives 'hot' refrigerant vapour direct from the compressor.
Cool air passing over the condenser reduces the temperature of the 'hot' refrigerant vapour and allows it to condense into a liquid which collects at the bottom part of the condenser.
3 - The Receiver/Drier
Next is the receiver/drier which receives the 'high-pressure' liquid refrigerant from the condenser. The receiver/drier has two functions, firstly it provides a means of storing a sufficient quantity of liquid refrigerant for effective running of the system and secondly, it absorbs moisture from within the system by means of dessecant.
Over a period of time, the receiver/drier will loose its efficiency (much the same as an oil or fuel filter does). Therefore, Red Dragon Air Conditioning recommends the receiver/drier be changed every 2 years or following any major repairs to the system.
Note: Systems fitted with an 'orifice tube' metering device are fitted with an accumulator instead of a receiver/drier (See 'Metering Devices').
Metering Devices
Liquid refrigerant (still under 'high pressure') leaves the receiver/drier and is delivered to the 'metering device'. In the diagram above, the 'metering device' is an expansion valve. The expansion valve meters the amount of refrigerant entering the evaporator based on evaporator temperature and system demand.
The metering device acts a restrictor and releases a mixture of liquid and vapour refrigerant into the evaporator at a 'low pressure'. Lowering the pressure of the refrigerant also lowers its temperature (as there is a direct pressure/temperature relationship). As this mixture passes through the evaporator it is transformed into a low pressure vapour due to the incoming warm air passing across the fins of the evaporator. Also, as the heat is being transfered from the incoming air to the fins of the evaporator, this now allows cooled air to flow into the cabin of the vehicle.
Metering Devices Cont'd
As previously mentioned, some vehicles are fitted with an 'orifice tube' metering device. These metering devices serve the same purpose as the expansion valve but are located inside the refrigerant pipe. When refering to an air-conditioning system, it is common to use the terms 'Expansion Valve' or 'Orifice Tube' to describe or identify the system in question.
Also, the 'orifice tube' system utilises an 'accumulator' which is located between the evaporator and the compressor and is designed to prevent liquid refrigerant entering the compressor.
The Evaporator
The purpose of the evaporator is twofold:
Firstly, it removes heat from the incoming air thus allowing cooled air to pass into the cabin of the vehicle and;
Secondly, it utilises the heat removed from the incoming air to raise the temperature of the refrigerant inside the evaporator and transform it back into a vapour form before returning to the compressor.
Constant Cycle
Refrigerant vapour then leaves the evaporator and is drawn back into the compressor where the cycle repeats itself.
How it Works!
Air Conditioning (A/C) systems are becoming more and more complex with the ever increasing advances in technology. So, in an attempt to keep things fairly simple for the average vehicle technician, enthusiast or the genuinely interested, we will take a look at a typical air conditioning system by taking each of the main components in-turn and describe their location and function within the A/C system.
1 - The Compressor
Let's begin with the heart of the system, the compressor. There are a number of different types of compressor currently used in modern vehicles including piston, rotary vane, scroll wobble plate, magnetic clutch and even clutchless. Despite this, all these compressors have a common purpose - which is threefold:
Firstly, the compressor must transfer refrigerant (for the cooling effect) and oil (for the lubrication of component parts) around the system. Secondly, the compressor must increase the pressure (and thus the temperature) of the refrigerant before it enters the condenser. And thirdly, the compressor must draw low pressure refrigerant from the evaporator in order to repeat the cycle.
The compressor is located at the front left or front right of the engine where its pulley is driven by the auxillary drive belt. It draws cool refrigerant vapour from the 'low pressure' lines and compresses it into 'hot - high pressure' vapour for delivery to the condenser.
2 - The Condenser
The condenser is located at the front of the engine compartment (in front of the radiator) and receives 'hot' refrigerant vapour direct from the compressor.
Cool air passing over the condenser reduces the temperature of the 'hot' refrigerant vapour and allows it to condense into a liquid which collects at the bottom part of the condenser.
3 - The Receiver/Drier
Next is the receiver/drier which receives the 'high-pressure' liquid refrigerant from the condenser. The receiver/drier has two functions, firstly it provides a means of storing a sufficient quantity of liquid refrigerant for effective running of the system and secondly, it absorbs moisture from within the system by means of dessecant.
Over a period of time, the receiver/drier will loose its efficiency (much the same as an oil or fuel filter does). Therefore, Red Dragon Air Conditioning recommends the receiver/drier be changed every 2 years or following any major repairs to the system.
Note: Systems fitted with an 'orifice tube' metering device are fitted with an accumulator instead of a receiver/drier (See 'Metering Devices').
Metering Devices
Liquid refrigerant (still under 'high pressure') leaves the receiver/drier and is delivered to the 'metering device'. In the diagram above, the 'metering device' is an expansion valve. The expansion valve meters the amount of refrigerant entering the evaporator based on evaporator temperature and system demand.
The metering device acts a restrictor and releases a mixture of liquid and vapour refrigerant into the evaporator at a 'low pressure'. Lowering the pressure of the refrigerant also lowers its temperature (as there is a direct pressure/temperature relationship). As this mixture passes through the evaporator it is transformed into a low pressure vapour due to the incoming warm air passing across the fins of the evaporator. Also, as the heat is being transfered from the incoming air to the fins of the evaporator, this now allows cooled air to flow into the cabin of the vehicle.
Metering Devices Cont'd
As previously mentioned, some vehicles are fitted with an 'orifice tube' metering device. These metering devices serve the same purpose as the expansion valve but are located inside the refrigerant pipe. When refering to an air-conditioning system, it is common to use the terms 'Expansion Valve' or 'Orifice Tube' to describe or identify the system in question.
Also, the 'orifice tube' system utilises an 'accumulator' which is located between the evaporator and the compressor and is designed to prevent liquid refrigerant entering the compressor.
The Evaporator
The purpose of the evaporator is twofold:
Firstly, it removes heat from the incoming air thus allowing cooled air to pass into the cabin of the vehicle and;
Secondly, it utilises the heat removed from the incoming air to raise the temperature of the refrigerant inside the evaporator and transform it back into a vapour form before returning to the compressor.
Constant Cycle
Refrigerant vapour then leaves the evaporator and is drawn back into the compressor where the cycle repeats itself.
