Checking of A/C System for Pressure Leaks
After completing the evacuation, close manifold gauge high pressure valve (HI) and low-pressure valve (LO) and wait 10 minutes. Verify that low-pressure gauge reading has not changed.
CAUTION:
If the gauge reading moves closer to "O", there is a leak somewhere. Inspect the tubing connections, make necessary corrections, and evacuate system once again, making sure that there are no leaks.