Screw Air Compressor High Temperature Fault: 4 Main Causes and Practical Solutions

High temperature is one of the most common and hidden problems in screw air compressors. When the discharge temperature rises above 105°C (some models alarm at 110°C), the machine may stop automatically. Long-term overheating is even more dangerous. It can speed up oil oxidation, damage seals, and in severe cases cause rotor seizure or complete compressor failure.

This article explains the warning signs, main causes, and easy troubleshooting steps for high temperature faults, helping you keep your screw air compressor running safely and efficiently.

1. Warning Signs and Risks of High Temperature

Before troubleshooting, you should recognize the typical signs of overheating:

• “High discharge temperature” alarm on the control panel

• Compressor casing feels extremely hot

• Lubricating oil turns dark quickly (normal oil should be light yellow or clear)

• Unusual noise during operation

If high temperature continues for a long time, it can cause serious damage:

• Oil life reduced by more than 50% (synthetic oil rated for 8000 hours may fail after 3000 hours)

• Faster aging of rubber seals, leading to oil leaks and air leaks

• Oil film breakdown between rotors, causing metal-to-metal contact and possible main unit failure within hours

2. 4 Main Causes of High Temperature in Screw Air Compressors

High temperature usually has more than one cause. Follow the order below to find the problem quickly.

1) Cooling System Problems (Most Common Cause)

The cooling system removes heat from the compressor. Problems differ between air-cooled and water-cooled models.

Air-cooled compressors

Common issues: blocked radiator or fan failure.

Check steps:

• Stop the machine and inspect the radiator. Dust and oil dirt reduce heat dissipation. Clean it with compressed air from the inside out.

• Check if the cooling fan is running. If not, inspect wiring or replace the fan motor.

• If the fan runs but airflow is weak, check for damaged fan blades.

Water-cooled compressors

Common issues: insufficient cooling water or blocked pipes.

Check steps:

• Ensure the inlet valve is fully open and water pressure is between 0.2–0.4 MPa

• Inspect pipes for scale buildup, especially in hard water areas

• Flush the heat exchanger with clean water in reverse direction if needed

2) Lubricating Oil Problems

Lubricating oil cools the compressor and lubricates the rotors. Oil problems are a major cause of overheating.

Check steps:

• Stop the machine for 10 minutes and check oil level. It must be between MIN and MAX

• If oil is dark, brown, or contains impurities, replace it completely and clean the oil tank

• Check the oil filter. If pressure difference exceeds 0.15 MPa, replace the filter immediately

3) Oil-Air Separator Blockage

A blocked oil-air separator increases internal pressure and exhaust resistance, which raises temperature.

Check steps:

• Check separator pressure difference. If it exceeds 0.2 MPa (some models 0.18 MPa), the separator is blocked

• Remove and inspect the separator element. Replace it if it is dirty or covered with oil sludge

• After replacement, check for oil accumulation inside the oil tank and clean if necessary

4) Environment and Load Issues

External factors are often ignored but can strongly affect temperature.

Check steps:

• Ensure good ventilation in the compressor room. Ambient temperature should be below 40°C

• Keep the compressor away from heat sources such as boilers or ovens

• Avoid long-term full-load operation above 90% of rated capacity. Reduce air demand or add another compressor if needed

3. Daily Maintenance Tips to Prevent High Temperature

Good habits can prevent most overheating problems:

1. Clean the cooling system regularly

   • Air-cooled: clean radiator every 2 weeks

   • Water-cooled: clean water system every 3 months

2. Replace oil and filters on time

   • Mineral oil: every 2000–3000 hours

   • Synthetic oil: every 8000–12000 hours

   • Oil filter: replace with every oil change

   • Oil-air separator: replace every two oil changes

3. Monitor discharge temperature daily

   • If temperature rises 5–10°C higher than normal, inspect immediately even if no alarm appears

Conclusion

High temperature in a screw air compressor is not a complex problem. In most cases, you can find the cause by checking cooling system, lubricating oil, oil-air separator, and operating environment in order. Regular maintenance and early detection can prevent shutdowns, extend compressor life, and reduce operating costs.