Your screw air compressor just tripped on high temperature, and the production line is down. Over a 10-year ownership period, electricity typically makes up around 80% of the total cost of a screw compressor – but a hot-running unit burns more of it, and every unplanned stop costs output you never get back. This guide explains what causes a screw air compressor high temperature trip and how to fix it before the next one.

A high temperature trip rarely appears from nowhere. The controller watches discharge temperature and stops the machine as it climbs toward the shutdown limit, protecting the air end, motor, and oil. Most oil-injected screw compressors are designed to run with discharge temperatures in the 80-95 C range, with shutdown typically triggered around 105-110 C. The protection is doing its job – the question is what is pushing temperature toward the limit.

The Real Cost of a High Temperature Trip

If the trip repeats weekly, that is 50 or more unplanned shutdowns a year. Even a 30-minute stop disrupts shift flow, and a serious failure forces an emergency service call at premium rates. Worse, each overheating event accelerates oil breakdown. Heat converts lubricant into varnish and carbon, which clog filters, insulate coolers, and slowly destroy the air end – turning a routine repair into a replacement.

Screw Air Compressor High Temperature Trip: 7 Causes and Fixes

• Poor ventilation or high ambient temperature – the most common cause. Hot air recirculating around the unit pushes discharge temperature up. Improve airflow and keep the intake away from heat sources.
• Low oil level or degraded oil – oil is the compressor’s coolant. Top it up to the correct level and change it on the manufacturer’s schedule.
• A clogged oil cooler – dust and dirt on air-cooled fins, or scale in water-cooled tubes, block heat rejection. Clean the cooler on a regular schedule; in dusty plants, inspect it monthly.
• A stuck thermostatic valve – if the bypass valve fails, oil can stop flowing through the cooler, and temperature climbs fast.
• A clogged oil filter or separator – restricted oil flow starves the air end of cooling oil and raises temperature.
• A faulty temperature sensor or controller – a false reading can trip a healthy machine. Compare the reading with a calibrated gauge.
• Oversized duty or a dirty intake filter – running beyond the unit’s design load, or restricting inlet air, forces the machine to work hotter than it should.

How to Stop the Next Trip

Start with the cheap checks: ventilation, oil level, and cooler condition. Then work through the thermostatic valve, filters, and sensor. Keep a log of discharge temperature so you can spot a rising trend before the trip happens – a machine that runs 5-10 C hotter than last month is telling you something.

Two numbers make the case for acting early. First, for every 10 C rise in operating temperature, lubricant life roughly halves – a unit running at 110 C instead of 90 C ages its oil about four times faster. Second, a compressor that trips weekly costs you roughly 50 production events a year. Fixing the cause once is far cheaper than the accumulated downtime.

FAQs: High Temperature Trips

Can I restart the compressor right after a trip? Only after you have found and corrected the cause. Restarting blindly repeats the trip and adds thermal stress. Check ventilation, oil, and cooler first, then restart and watch the temperature.

Is it safe to bypass the high-temperature switch? No. Bypassing the protection lets the machine overheat until the oil breaks down and the air end scores – a failure that can cost far more than the downtime you were trying to avoid.

Prevent It Before It Costs You a Shift

A screw air compressor high temperature trip is a warning you should never ignore. Catch the cause early – ventilation, oil condition, cooling, and sensors – and the unit keeps running at full output. If you are planning a replacement, look at a variable-speed model: it runs cooler and lighter at partial load and is installed with proper ventilation in mind. Our rotary screw air compressor range covers fixed-speed and variable-speed machines; contact our team with your plant’s heat load and duty cycle, and we will help you pick a unit that stays cool under your conditions.