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Master Troubleshooting Guide
System-by-system reference with safety rules and cheat-sheet values.
Won't run
Electrical
Trips breaker or overloadWye-Delta starter problemContactor chattering or burningVSD (variable speed drive) faultMotor overload trips intermittently with no obvious causeMotor hums, overheats, or trips — one phase lostVSD trips on DC bus overvoltage during decelerationVSD trips on overcurrent or ground fault at start
Pressure
Low discharge pressure / won't build pressureDischarge pressure too high / safety valve liftingShort cycling (loads/unloads rapidly)Long pump-up timeBlowdown/vent valve leaks air continuously after shutdownInlet/unloader valve stuck (open or closed)Minimum pressure valve / check valve not holding sump pressureSafety/relief valve pops or leaks at the seatAdequate tank/line pressure but low flow (CFM) at point of useSystem pressure swings / unstable regulationLarge pressure drop between compressor room and point of useCompressor runs far more than the plant needs (leak load)Tank check valve leaking back (air hisses from unloader after shutdown)Check valve stuck closed / restricted — pump builds heat, pops relief, tank doesn't fillPiston compressor runs but won't build pressure (stalls at low psi or tank stays at 0)Rotary screw runs loaded but won't reach set pressureCompressor takes much longer to fill tank than it used toIntercooler safety valve popping on two-stage compressorTank loses pressure overnight / when shut offTank safety valve popping on a piston compressor
Temperature
Controls
Controller / HMI shows fault but won't clearWon't transition between load and unloadController/PLC communication fault or lost networkMultiple compressors not sequencing correctly (lead/lag/trim)E-stop or safety circuit will not resetController shows an impossible temperature or pressurePressure switch won't shut compressor off (runs past cut-out, safety valve pops)Pressure switch won't restart compressor when pressure dropsPressure switch chattering, buzzing, or rapid on/off clickingAir leaking from pressure switch unloader while running (or never bleeds)Need to change cut-in / cut-out pressure (switch won't hold settings)
Lubrication
Low oil pressure trip (screw)High oil consumption (reciprocating)Oil foaming or high oil consumption with foam visible in sight glassOil found in downstream air lines despite separator in good conditionOil leaking at motor/airend shaft seal or coupling areaOil level falls with no visible leakWrong oil added, or two fluids mixedOil analysis report flags wear metals or contaminationOil blowing out of breather or into the tank / air lines on a piston compressor