After using the vacuum packaging machine for a period of time, it was found that the vacuum lid could not be sucked. At this time, you can check the machine whether has following problems.
1. Check the vacuum chamber lid is flat. (you need to turn off the power first, to confirm that the lid is no unevenness or the lid is tightly closed with the chamber)
2. Check limit switches (either broken or just screws are loose). There are 2 limit switches, one on each side of the chamber.
After the power is on, press the limit switch first.
If both vacuum pump and solenoid valve have sound, it indicates limit switch is still good, as long as the screw on the base of the limit switch need to be adjusted.
If you press the limit switch, there is no sound from solenoid valve and vacuum pump, it means that the limit switch is broken and needs to be replaced.
3. Check all power (input and output). Whether any wires have fallen off, if no, it is likely that the vacuum pump has problems.