ABB ACS580 A4A3 Fault Code — What It Means
The fault code A4A3 does not appear in official ABB ACS580 documentation. The code you are seeing is most likely A4A0 (Control Board Temperature) or a PU communication error such as 5681. A4A0 means the internal temperature of the control board has exceeded the safe operating limit, triggering a thermal shutdown to prevent permanent damage to the electronics. If your display strictly reads A4A3 and not A4A0, it is possible the drive is reporting a Power Unit communication failure (often code 5681), which shares similar symptoms of the control unit being unable to function due to power or signal issues.
For A4A0, the drive is protecting itself from heat damage caused by inadequate cooling. For PU communication faults, the 24V supply to the control board or the connection between the control unit and power unit has failed. Either fault will prevent normal operation until the underlying issue is resolved.
Before You Replace Anything
Technicians often replace the entire control board when the real problem is a failed cooling fan or a clogged vent. Check the fan operation and clean all vents before ordering a new board.
Common Causes
- Cooling fan failure (~40%) The control board cooling fan is not spinning, has a broken connection, or is clogged with dust, preventing heat removal from the electronics.
- Blocked airflow (~30%) The drive is installed in a confined space, the front cover is missing or loose, or ventilation vents are obstructed, restricting the designed airflow path.
- 24V supply failure (~15%) The internal 24V supply of the power unit is not functioning, or the external 24V supply (if parameter 95.04 is set to 1) is dead, causing a PU communication fault.
- High ambient temperature (~10%) The surrounding environment is too hot (consult your model’s temperature table) without external cooling, causing the control board to overheat.
- Connection fault between CU and PU (~5%) The cable connecting the Control Unit to the Power Unit is loose or damaged, preventing communication and triggering a fault.
Quick Diagnosis
Answer these to narrow it down fast.
Does the cooling fan spin when the drive is powered on?
No: The fan is failed or disconnected. Inspect the fan connection at the control board and replace the fan if needed.
Is the front cover installed and tightened?
No: Install and tighten the front cover. The ACS580 requires the cover for proper airflow and will overheat without it.
Does the fault code read exactly A4A0 or something else like 5681?
No: If the code is 5681 or another communication fault, check parameter 95.04 and the 24V supply to the control board.
Step-by-Step Fix
- Verify the fault code on the keypad and note any auxiliary code (e.g., A4A0-1 or A4A0-2) which specifies which fan or sensor triggered the fault.
- Power down the drive and wait for all capacitors to discharge (consult the drive manual for safe lock-out procedures) before opening the enclosure.
- Inspect the cooling fan by removing the front cover and checking that the fan spins freely by hand and is free of dust or debris.
- Clean all vents and the fan using compressed air, blowing away any accumulated dust or obstructions in the airflow path.
- Check the fan connection at the control board terminal and measure voltage at the fan terminals if the fan is not running when the drive is powered on.
- Verify parameter 95.04 (Control Board Supply) matches the physical setup (0 for internal 24V, 1 for external 24V) and measure 24V DC at the CU-PU connection points if a communication fault is present.
- Replace the fan assembly if the fan is faulty or does not spin, and reboot the control unit using the drive parameters after repairs are complete.
Parts Often Needed
| Part | Notes |
|---|---|
| ABB ACS580 Cooling Fan Assembly | Amazon | Match the fan part number to your specific drive frame size and voltage rating |
| ABB ACS580 Control Board (CU) | Amazon | Only needed if the board itself is damaged or the 24V supply has failed internally |
When to Call a Pro
Call a qualified industrial electrician or VFD technician if you are not trained in safe lock-out/tag-out procedures for high-voltage equipment. Even after power-down, the ACS580 retains dangerous DC bus voltages in its capacitors. A professional can safely diagnose whether the fault is a simple fan replacement, a control board failure, or a power unit issue requiring replacement of major components. If the fault persists after cleaning and fan replacement, or if you measure no 24V supply at the control board, the drive may need factory-level service or board replacement that requires programming and commissioning.
Rough cost: A pro service call runs about $150-400.