The theory of refrigeration is that the refrigeration system uses four basic principles to operate

1.Heat always flow from a warmer point to a cooler point

2.Flow is always from a higher pressure area to a lower pressure area

3.Heat must be added to or removed from a substance before a change in state can accur

4. The temperature at which a liquid or gas changes staate depends on the pressure

The Refrigeration cycle starts at the compressor,when the compressor start it creates a low pressure in the suction line which pulls refrigerant gas(VAPOR) into the compressor.

The compressor compress the refrigerant raising its pressure and temperature,the refrigerant leaves the compressor through the discharge line as a hot high pressure gas,

The refrigerant enters the condenser coils where some of the heat will be lost, the condenser fan blows air across the finned surface of the condenser coils.

When enough heat is removed from the refrigerant  it will condense(change to liquid) the refrigerant leaves the condenser as warm high pressure liquid,it then passes through the filter dryer,the filter dryer trap any moisture or other contaminant that might be in the sealed system.

The liquid refrigerant then enters the capillary tube,the capillary tube is a very small tube that acts like a metering device it measures the amount of refrigerant entering the evaporator.

Since the evaporator is under a lower pressure than the liquid line--by the suction that is created by the compressor,as the liquid enters the evaporator coil the large area and the lower pressure allows the refrigerant to expand,and lower its temperature.

Since the evaporator fan is moving the air across the finned surface of the evaporator coil the expanding refrigerant absorbs some of the heat,this results in a lowering of the indoor air temperature and the cooling  starts.

The expanding and absorbing of heat causes the liquid refrigerant to evaporate and change back to gas--the refrigerant then returns to the compressor and the cycle is repeated.