A major air leak can prevent the pressure levels from being low enough to turn on the MS. Possible causes of a major leak might be a loose or disconnected fitting or an improperly positioned or damaged O-ring.
Procedure
- Listen for a rush of air or a hissing sound coming from the MS.
- If you do not hear these sounds, there is no air leak.
- If you hear these sounds, continue to step 2.
- Shut down the MS for service. See Shut Down the MS.
- Visually inspect the vacuum system and vacuum lines for leaks.
- Check each fitting and flange on the system for tightness, and tighten any that are loose.
- Do not tighten fittings indiscriminately. Pay particular attention to fittings that have been changed recently and fittings that have been subjected to heating and cooling.