DUOYI DY522A Vacuum Operation
A. Turn off the blue and red valves.
B. Turn on the device. Check the LCD shows "vacuum test" mode. If not, press the Function key to switch to it.
C. Press Unit key to set the reading units.
D. If numbers show on startup, hold Zero key until cleared to zero.
E. Connect the device to the A/C system following the diagram. Note refrigerant flow direction! (Temperature sensors won't affect operation.)
F. Open blue and red valves. Start the vacuum pump.
G. After vacuum complete, close valves and turn off pump.