danfoss al 38 alarm

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In Danfoss VFD, Alarm 38 (often displayed as AL 38 or A38) stands for Internal Fault. This is a general error that occurs when the drive’s internal self-diagnostics detect a failure in the communication or hardware between the control card and the power card. Because this is an internal hardware check, it is usually a "Trip Lock" alarm, meaning the drive will not allow a restart until the issue is cleared.

danfoss al 38 alarm

 

Common Causes

  • Communication Loss: The internal ribbon cable or connector between the control card (where the keypad/terminals are) and the power card (the main body of the drive) has become loose or oxidized.

  • Electrical Noise (EMI): High frequency interference is disrupting the internal data flow.

  • Option Card Conflict: A newly installed fieldbus or I/O option card is not seated properly or is defective.

  • Hardware Failure: A component on the control or power board has failed (e.g., a dried-out capacitor or a faulty EEPROM).

Troubleshooting Steps

1. Cycle the Power

Turn off the main power to the drive. Wait for the display to go completely dark (usually 5–15 minutes depending on the drive size) to allow the capacitors to discharge. Turn the power back on. Sometimes a simple "hard reset" clears a temporary glitch.

2. Reseat the Control Card & Keypad (LCP)

If the drive is powered down and safe:

  • Remove the LCP (keypad) and plug it back in firmly.

  • If you are comfortable opening the drive, ensure the control card is pushed firmly into its sockets on the power card. Vibration can sometimes wiggle these loose over time.

3. Check for "Sub-codes"

If you have a Graphical LCP, look for a sub-code (a 4-digit number like 2561 or 1280).

  • Sub-code 1280: Usually indicates a power card data error.

  • Sub-code 2561: Usually points to an internal communication timeout.

  • Having this code ready will help Danfoss Technical Support identify the exact failed component.

4. Perform a Manual Initialization (Last Resort)

If the hardware isn't physically broken, a "Two-Finger" or "Three-Finger" reset might clear a corrupted memory:

  1. Turn power OFF.

  2. Press and hold [Status], [Main Menu], and [OK] simultaneously.

  3. Turn power ON while holding the buttons until the display says "Initializing."

  4. Warning: This will erase all your parameters and return the drive to factory settings.

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