HAAS® Alarm 120 — LOW AIR PRESSURE
Part of: our HAAS® alarm reference · covering 60 of the most common alarms.
What it means
Shop air supply has dropped below the minimum the machine needs. Most HAAS®<sup class="reg">®</sup> machines need around 85–100 psi.
Common causes
- Compressor not keeping up
- Big leak somewhere on the line
- Pressure regulator drifted
- Filter blocked
What to check first
- Check the gauge on the machine's air regulator
- Listen for any obvious leaks (hissing)
- Check compressor is on and not in cool-down
Prevention
Tool-changer faults are almost always either air pressure or chip contamination. Keep shop air at 85–100 psi clean and dry, and clear chips and coolant residue from the changer area weekly. On lathes, check turret lubrication monthly. If you have an intermittent fault that disappears when you reset, don't ignore it — book it in before it becomes a hard fail.
If you’re still stuck
If you’ve worked through the checks above and the alarm hasn’t cleared — or if it cleared and came back — that’s the point to call. Persistent alarms after a reset usually mean a real component fault, and pushing through them risks turning a simple repair into a bigger one. Keith covers HAAS® breakdowns across the UK with same-day phone diagnosis.
A note on this guide. Alarm wording and numbering can vary by HAAS® machine model and software revision. The descriptions here are written in plain English to help you understand what the machine is reporting and what to check first — they’re not a substitute for the official HAAS® operator manual or for a qualified service engineer’s diagnosis. Always confirm the exact alarm message on your screen and consult your machine’s documentation before attempting any repair.