Fixed Throttle Valve (Orifice)

1. Inlet on the high pressure side
2. Filter insert
3. Internal diameter of the throttle valve
4. O-ring
5. Outlet on the low pressure side.

The fixed throttle valve is a passive flow regulator. It consists of a thin metal pipe which is positioned in a plastic housing with a filter on both the intake and outlet sides. The filter collects any impurities in the system.

The throttle valve governs the volume of refrigerant which is released from the evaporator. The volume is affected by the dimensions of the pipe (diameter, length) and the pressure and temperature on both sides of the pipe.

The throttle valve is located in the evaporator inlet pipe.

The location of the throttle valve can be seen from the outside, as there is a projection in the line. When the air conditioning system is in operation, this point constitutes the transition between the hot and the cold areas.

Upstream of the choke valve is the refrigerant in liquid form at high pressure.

The liquid refrigerant flows out under high pressure from the compressor to the inlet side of the throttle valve (1). Two O-rings prevent the refrigerant from flowing past the throttle valve.

Two filter inserts in the inlet and the outlet of the throttle valve clean the refrigerant of particles. The filter insert on the outlet side also serves to further distribute the refrigerant.

The calibrated inner diameter (3) of the throttle valve only allows a volume of refrigerant to pass that corresponds to the pressure. This limits the volume of refrigerant that flows through.