1
No incoming power
CheckVerify voltage at disconnect L1-L2-L3 with meter.
FixRestore power; check upstream breaker, fuses.
2
Tripped overload relay
CheckCheck OL reset on starter; look for thermal trip indicator.
FixReset; investigate root cause (high amps, single-phasing, low voltage).
3
Pressure switch open (system at cut-out pressure)
CheckBleed tank below cut-in pressure; listen for switch click.
FixIf no click, replace pressure switch.
4
Pressure switch unloader stuck
CheckListen for air bleed on shutdown.
FixClean or replace unloader valve in pressure switch.
5
Faulty contactor coil
Check24/120/240V at coil terminals when start signal present.
FixIf voltage present but no pull-in, replace contactor.
6
Control transformer fuse blown
CheckContinuity across control fuse.
FixReplace fuse; check for short on control circuit.
7
Emergency stop / interlock open
CheckTrace control wiring; check door interlocks, high-temp switch, oil-level switch.
FixReset/repair failed interlock.
Safety
Lockout/tagout before opening enclosures. Verify zero energy. Bleed system pressure before opening any pneumatic connection.