You can adjust valves with standard service valve wrenches or screwdrivers. For an illustration of this, see Table 1. You can change all range valve settings quickly from low-range refrigerants, such as R134, to high-range refrigerants, such as R22, or from high range refrigerants to low-range refrigerants. To raise the valve opening point, turn the adjustment screw located at the top of the range spring housing counterclockwise. See Table 1 and Figure 1. Turn the adjustment screw clockwise to lower the opening point. You can make exact settings with a pressure gauge in the refrigerant line to determine the throttling point. Put the system under normal operating load and adjust to the operating pressure that you need. See Table 4 for pressure range specifications.
|Valve size, in.
|Range adjustment screw
|3/8, 1/2, 3/4
|1/4 in. square head adjustment screw with a screwdriver slot
|1, 1 1/4, 1 1/2
|5/16 in. square head adjustment screw
|2, 2 1/2
|1/2 in. square head adjustment screw and a slotted cam
If the compressor operates in high ambient temperatures, head pressures may remain high enough during off cycles to prevent the valve from closing completely. In such instances, raise the opening point of the valve just enough to cause the valve to close during compressor standby periods. This also raises the throttling point.