A/C System Function
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The compressor (4) pulls low-temp./press. refrigerant vapor (11) from the accumulator (3) and raises its pressure & temperature. As it flows through the condenser ( 8 ), the refrigerant's higher-than-ambient temperature causes heat to flow out into the airstream, allowing the refrigerant to condense into a high-temp./press. liquid (14). The pressure is a result of the precise restriction caused by the orifice tube (9). As the refrigerant flows slowly through it, the pressure drops suddenly, causing the refrigerant to flash-boil from a low-press. liquid (13) into a low-temp./press. vapor (11). To change from liquid to vapor, the refrigerant must absorb heat through the evaporator, which cools the cabin airstream. The refrigerant then returns to the accumulator where it continues to boil & is dried by a desiccant.
If refrigerant leaks out OR the cabin airstream is too cold, the pressure in the evaporator will be too low to keep the cycling switch (2) ON below ~20psi. If the system is overcharged OR the ambient airstream is too hot, pressure in the condenser will cause the pressure cut-off switch (6) to turn OFF above ~400psi. If that fails, then the pressure relief valve (5) will vent refrigerant above ~500psi.
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