When a compressor trips the breaker or stops on an alarm, a protection has reacted. Restarting without looking for the cause only postpones the breakdown, sometimes making it worse. Here is how to find your way.
Safety: diagnosis inside an electrical cabinet is done by a qualified person. Machine locked out, receiver vented.
The workshop breaker trips at start-up
- Unsuitable protection: starting a motor draws more current than normal running. A breaker that is too small or has the wrong curve trips at every start. The protection is chosen according to the machine's manual.
- Cable too long or too thin: the voltage drops at start-up and the motor strains.
- A missing phase on a three-phase machine: the motor cannot start properly.
- An insulation fault (damaged motor or cable, damp): the residual current device then trips. Do not keep resetting it: have it checked.
With a variable speed compressor, starting is gradual: the inverter limits the inrush current. If it still trips, the problem usually lies in the installation or a fault that needs diagnosing.
The compressor stops and shows an alarm
The controller stops the machine to protect it. Write down the exact message, then:
- temperature alarm: room ventilation, dirty cooler, oil level (see compressor overheating);
- motor overload: the machine is straining. Pressure set higher than intended, clogged air/oil separator, voltage too low;
- inverter fault: often linked to the power supply or the cabinet temperature. Diagnosis is for service;
- rotation direction or phase fault: after work on the electrical installation, this is the first thing to have checked.
The compressor starts too often
A motor that starts and stops constantly heats up and eventually trips its protections. The usual causes: leaks in the network, a receiver that is too small, too small a gap between stop and restart pressure. See compressor runs constantly or restarts too often and air receiver sizing.
The right reflexes
- Note the alarm message and the time.
- Check what can be seen without dismantling anything: ventilation, cooler, oil level, pressure gauge.
- Reset once. If the fault comes back, leave the machine stopped.
- Make a service request from the warranty and service page with the model, serial number, hour meter, message and photos of the screen.
Other symptoms are covered in our compressor troubleshooting guide.