Air Compressor Fault Finding Guide

Air compressor problems can cause costly downtime, reduced productivity and expensive repairs if left unresolved. This fault-finding guide covers some of the most common air compressor faults, their likely causes and the checks you can perform before calling an engineer.

Before You Start Fault Finding

Before investigating any air compressor fault, always isolate electrical power and release stored air pressure where safe to do so. Many compressor issues can be caused by simple problems such as blocked filters, air leaks, incorrect settings or electrical supply issues. Checking these items first can often save significant time and expense. Common troubleshooting guidance recommends checking power supply, filters, oil levels, pressure settings and visible leaks before moving on to more complex diagnostics.

Air Compressor Won't Start

Possible Causes:

• No electrical supply.
• Tripped circuit breaker or blown fuse.
• Faulty pressure switch.
• Failed motor capacitor.
• Motor overload trip activated.
• Control circuit fault.

Checks:

• Verify incoming power supply.
• Check breakers and fuses.
• Inspect pressure switch operation.
• Reset overloads where appropriate.
• Check for humming motors indicating capacitor issues.

Pressure switch faults, power supply issues and failed start capacitors are among the most common causes of compressors failing to start.

Air Compressor Runs But Won't Build Pressure

Possible Causes:

• Air leaks.
• Blocked filters.
• Worn piston rings.
• Faulty check valve.
• Pressure switch problems.
• Excessive site air demand.
• Loading or unloading valve faults.

Checks:

• Inspect the compressed air system for leaks.
• Check air filters and separators.
• Inspect non-return valves.
• Review compressor loading controls.
• Confirm air demand is not exceeding compressor capacity.

Pressure loss is often caused by leaks, restrictions, worn components or demand exceeding compressor output rather than the compressor itself.

Low Air Pressure

Possible Causes:

• Air leaks in the pipework.
• Blocked filters.
• Separator element restriction.
• Incorrect pressure settings.
• Undersized compressor.
• High system demand.

Low pressure complaints are frequently linked to leaks, restrictions, saturated separator elements or excessive air consumption elsewhere in the system.

Air Compressor Overheating

Possible Causes:

• Dirty coolers.
• Low oil level.
• Poor ventilation.
• Blocked filters.
• High ambient temperatures.
• Incorrect lubricant.

Checks:

• Clean coolers and ventilation paths.
• Check oil condition and level.
• Inspect cooling fans.
• Ensure adequate room ventilation.

Excessive Oil Carryover

Possible Causes:

• Failed separator element.
• Incorrect oil level.
• Blocked return line.
• Worn internal components.
• Incorrect operating pressure.

If oil is appearing in the air system, separator elements, oil levels and return line operation should be checked as part of routine diagnosis.

Air Leaks

Compressed air leaks are one of the most common and expensive faults found on industrial compressed air systems. Even small leaks can significantly increase energy consumption and prevent compressors from reaching their target pressure. Troubleshooting guides consistently identify leaks as a major cause of pressure loss and poor system performance.

• Listen for audible leaks.
• Inspect hoses and fittings.
• Check drain valves.
• Inspect flexible connections.
• Consider a professional leak survey for larger systems.

Common Air Compressor Faults at a Glance

Need Help Diagnosing a Compressor Fault?

If your air compressor is not building pressure, keeps tripping, overheats or has developed another fault, Airmatic Compressors can help. Our engineers diagnose and repair piston compressors, rotary screw compressors, dryers and compressed air systems throughout the UK.

Contact our team for technical advice, servicing, repairs and emergency breakdown support.