Air Conditioning

Principles of air conditioning

Expansion & Evaporation
The Mechanical refrigerant system moves by heat:

• The high temperature and high liquid refrigerant is stored in a receiver.
• The liquid refrigerant is released to the evaporator through the expansion valve
• The temperature and pressure of the liquid refrigerant is lowered and some of the liquid refrigerant changes to vapour. 
• The Low pressure, low temperature refrigerant flows into and evaporator where it boils and changes into a gas, removing heat from the surrounding air in the process.  

The Picture above shows the process

Condenser and Fan
Air conditioning works by way of evaporation to remove heat from the air. The REFRIGERANT GAS (Freon, R-134A, R-12, or whatever type) starts in the compressor, mounted on the engine, the gas is compressed into a high pressure. The gas then goes to the condenser which is mounted in front of the radiator and looks very much like the radiator. Inside the condenser, the gas is "condensed" which means it is converted to a liquid by having heat removed from it by way of the air flowing over the condenser. The liquid, still under high pressure is then sent to the evaporator. And the fan helps cool it down.


Dryer
They act as a temporary storage containers for oil and refrigerant when neither are needed for system operation (such as during periods of low cooling demand). This is the “receiver” function of the receiver/drier.


Evaporator, Blower and Drain tube
In a vehicle A/C system, cold, low-pressure liquid refrigerant enters the evaporator. Warm air from the interior of the vehicle passes through the evaporator by action of the blower fan. Since it’s a fact of nature that heat always travels from a warmer area to a cooler area, the cooler refrigerant flowing inside the evaporator’s absorbs heat from the warm air. At the same time, humidity in the air condenses on the cool evaporator’s surface, then eventually drips out of a drain tube to outside the vehicle


Expansion valve
Its job is to control flow, in this case, the amount of refrigerant entering the evaporator. Since system operating conditions vary (sometimes high cooling demand, sometimes low cooling demand) it is necessary to be able to adjust the amount of refrigerant entering the evaporator.


Compressor
Inside the compressor pump, a rotor spins at high speed. Similar to the way a turbine works, the spinning rotor pulls gases into the inlet and pushes them out the other side.The rotor inside the compressor is connected to the engine of the car using a belt.

WIRING DIAGRAM OF AC

Ignition switch needs it to be on but also the blower fan has to be on which will trigger the heater relay and you get a closed circuit.
Ac switch triggers the magnetic clutch

Heater relay controls the Ac switch