A compressor breakdown often means the whole workshop stops. The good news: many "breakdowns" have a simple cause that can be found in a few minutes. This guide helps you recognise the symptom, make the first checks safely, and know when to call a technician.
Safety first
- A compressor can restart on its own as soon as the pressure drops. Before opening a panel or removing anything, switch off and lock out the power supply, and vent the air from the machine and the receiver.
- The oil and some parts are very hot after running. Let them cool down.
- Never touch the setting of the safety valve and never block it: it protects the receiver.
- Electrical and internal work (inverter, motor, screw element) must be done by a trained technician.
Find the fault from the symptom
| What you notice | Most frequent causes | Detailed guide |
|---|---|---|
| The compressor will not start | power cut, missing phase, emergency stop pressed, active alarm, network pressure still high enough | compressor will not start |
| It trips or stops on a fault | unsuitable electrical protection, voltage drop, overheating, fault shown on the controller | compressor tripping |
| It overheats or stops on temperature | poorly ventilated room, dirty cooler, low oil level | compressor overheating |
| It will not build pressure | leaks, clogged air filter, demand higher than output, setting | compressor not building pressure |
| It runs constantly or restarts too often | leaks, receiver too small, undersized compressor, drain stuck open | compressor runs constantly |
| Oil in the air, oil consumption | saturated air/oil separator, oil level too high, wrong oil | oil in compressed air |
| Water in the network | no drain or blocked drain, no dryer, dryer fault | water in compressed air |
| The safety valve blows | working pressure too close to the set pressure, control fault, worn valve | safety valve blowing |
| Unusual noise or vibration | loose fixing, dirty fan, bearing or screw element wear | noise and vibration |
| Hissing in the workshop with machines stopped | leaks in the network | detect and repair leaks |
What you can check yourself
These checks are safe, with the machine stopped or from the controller screen:
- Read the message on the controller and write it down exactly. It is the first thing a technician will ask for.
- Note the hour meter and the date of the last service: a filter or separator at the end of its life explains many symptoms.
- Check the oil level in the sight glass.
- Look at the cooler and grilles: a layer of dust is enough to make the machine overheat.
- Listen to the network when machines are stopped: hissing means a leak.
- Check the drain on the receiver and filters: it must discharge water regularly.
When to stop the machine and call service
Stop the compressor and request a visit if you notice:
- smoke, a burning smell or a metallic noise;
- a lot of oil in the air or around the machine;
- an alarm that comes back after every restart;
- a safety valve blowing continuously;
- a breaker tripping at every start.
For a quick diagnosis, have the model, the serial number, the hour meter, the alarm message and a few photos ready. Make your request from the warranty and service page, or ask for a repair visit from the maintenance page: we intervene or offer a solution within 48 to 72 hours across the UK, with a hire compressor if the repair takes time.
Avoiding breakdowns: regular maintenance
Most breakdowns give warning: temperature creeping up, oil being used, pressure dropping. Maintenance by running hours prevents almost all of them. See screw compressor maintenance, the service schedule and piston compressor maintenance.