Expansion valve
The expansion valve regulates the amount of refrigerant that is released into the evaporator. The expansion valve is positioned in the engine compartment by the A/C hoses passage in the bulkhead.
The expansion valve consists of a spring-loaded ball which is located on the high-pressure side. The ball is connected via a pressure lever to a diaphragm in a gas-filled chamber on the expansion valve low-pressure side. The spring presses on the ball with a constant pressure. The pressure from the pressure lever depends on the pressure in the gas-filled chamber. The pressure in the gas-filled chamber depends on the refrigerant temperature in the evaporator outlet. If the temperature of the refrigerant that passes the expansion valve low-pressure side decreases, the pressure also decreases in the gas-filled chamber. The spring then presses the on ball and the pressure lever, the diaphragm cannot withstand the pressure and the expansion valve restricts the refrigerant flow proportional to the thermal load on the evaporator. If the temperature of the refrigerant increases (increased thermal load on evaporator), the pressure also increases in the gas-filled chamber. The diaphragm t
hen presses on the pressure lever and ball, the spring is compressed and the expansion valve opens.
