Why does my Atlas Copco compressor run but not load?
Short answer: Unit runs unloaded — will not load. If your Atlas Copco GA 30+-90 / GA 37+ (Elektronikon Touch) is showing Compressor starts but does not load after delay, the controller has logged a specific, documented condition. This page covers what it means, what causes it, what you can safely fix yourself, and when — and why — it takes a technician.
What exactly is the machine telling you?
Documented causes include too high temperature in the oil separator vessel (or defective temperature switch TSHH1), phase sequence relay K25 open, interrupted wiring, solenoid valve out of order, or the inlet valve stuck closed.
Which machines show this?
Atlas Copco's current-generation GA 30+ through GA 90 oil-injected rotary screws — the '+' models such as the GA 37+ — carrying the Elektronikon Touch controller with its color touchscreen. These are the newest machines in the GA line, and their instruction books lean on documented cause lists (oil level, cooling air, relay designations like F21, Q15, F15, K25) rather than bare code numbers, so faults often read as plain-language conditions. Practical tip: the manual warns that pressing the emergency stop does not make the compressor voltage-free — any electrical-cabinet check on these machines starts with switching off and locking out the supply, full stop.
What causes it?
- Oil separator vessel too hot (or its temperature switch TSHH1 defective), blocking the load command
- Phase sequence relay K25 open — typical after electrical work changed rotation
- Interrupted wiring or a failed loading solenoid valve
- Inlet valve stuck closed
Can you fix it yourself?
Partly — staff can rule out the temperature-related cause (ventilation, ambient, cooler cleaning) and listen for the loading solenoid. The rest is diagnosis, not repair.
Step by step — what to try, in order:
- Check for a temperature-related cause first: ventilation, ambient temperature, cooler cleanliness
- Listen/watch whether the loading solenoid clicks when the controller commands load
- Note whether the fault started after electrical work (phase sequence relay K25 opens on wrong rotation)
- Record the behavior for the technician — do not dismantle valves under pressure
When do you need a technician — and why?
Solenoid and inlet-valve replacement happens on a pressurized air circuit, and phase-rotation or wiring faults are electrical-cabinet work — both need a qualified technician.
If it does come to a service call and you're in Nashville, TN or Birmingham, AL, we maintain independently compiled lists of local companies that service industrial air compressors — real businesses with verified contact information, none of whom paid to be listed.
Related questions
What does Compressor starts but does not load after delay mean on an Atlas Copco GA 30+-90 / GA 37+ (Elektronikon Touch)?
Unit runs unloaded — will not load. Documented causes include too high temperature in the oil separator vessel (or defective temperature switch TSHH1), phase sequence relay K25 open, interrupted wiring, solenoid valve out of order, or the inlet valve stuck closed.
Can I fix Compressor starts but does not load after delay on an Atlas Copco GA 30+-90 / GA 37+ (Elektronikon Touch) myself?
Partly — staff can rule out the temperature-related cause (ventilation, ambient, cooler cleaning) and listen for the loading solenoid. The rest is diagnosis, not repair.
When does Compressor starts but does not load after delay on an Atlas Copco GA 30+-90 / GA 37+ (Elektronikon Touch) need a technician?
Solenoid and inlet-valve replacement happens on a pressurized air circuit, and phase-rotation or wiring faults are electrical-cabinet work — both need a qualified technician. Solenoid or inlet-valve replacement and any phase-rotation/wiring issue should go to a qualified technician.
Verified against service documentation: Atlas Copco GA 30+-90 / GA 37+ (Elektronikon Touch) documentation for Compressor starts but does not load after delay (manualslib.com)