Troubleshooting a Compressor That Won't Start
Compressor Type Matters
Not all air compressors are built the same. So the reason your machine won’t start might depend on what kind of unit you’re working with. Below, we’ve broken down the most common causes based on whether you own a reciprocating compressor, a portable rotary screw unit, or a stationary rotary screw compressor.
If You Have a Reciprocating or Portable Rotary Screw Compressor
These types of compressors are often used on jobsites or in light industrial settings. They’re relatively simple machines but still rely on the basics: clean power, good airflow, and the right oil level.
Check These First:
- Power Source: Make sure it’s plugged directly into a stable outlet (really). No extension cords. Look for tripped breakers or blown fuses.
- Oil Level: Low oil can trigger a safety shutdown. Most units have an oil sight glass. Top off as needed.
- Overload Reset: Many compressors have a reset button near the motor. Let the unit cool down and try pressing it.
- Pressure Switch: If it’s stuck or misadjusted, the machine may not know it needs to start.
If You Have a Stationary Rotary Screw Compressor
These are high-output machines found in manufacturing plants, production lines, and large facilities. They include control panels, sensors, and interlocks so when they don’t start, the issue is often more complex.
Start With These Checks:
- Controller Display: Look for fault codes or warnings on the display screen.
- Emergency Stop Button: Make sure it hasn’t been engaged. Reset if necessary.
- Incoming Voltage: Use a multimeter to verify correct voltage at the terminal block (3-phase units are common).
- Motor Overload or VFD Trips: Check if the motor starter or variable frequency drive has faulted out.
- Interlocks: Check for open panel doors, failed pressure sensors, or disconnected wires that may prevent startup.
If these don't work, schedule us for a service call for your stationary rotary compressor!
Preventive Tips for All Compressor Types
- Keep machines clean and well-ventilated to avoid overheating.
- Stick to a regular oil and filter change schedule.
- Inspect pressure switches, safety shutdowns, and wiring at least quarterly.
- If you’re using a rotary screw, review your service logs. Many units will show maintenance alerts before shutdowns occur.