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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

ALARM 38

Internal fault

Danfoss · VLT HVAC Basic FC 101

What does ALARM 38 mean?

An unspecified internal fault has occurred within the frequency converter. This indicates a potential hardware or firmware issue requiring specialized attention, and continued operation may cause further damage.

Common Causes

  • Transient voltage spike or electromagnetic interference (EMI) disrupting internal drive logic.
  • Corruption of firmware or internal configuration settings.
  • Hardware failure on the control card or power card (e.g., processor, memory).
  • Internal communication bus error between drive modules (e.g., control card to power card).
  • Overheating of internal components not detected by specific thermal sensors.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Perform a full power cycle of the drive (disconnect input power for at least 60 seconds) to reset all internal electronics.

  2. 2

    Record the exact fault code and any associated diagnostic or sub-code information displayed on the LCP (e.g., from P15-02 Fault Log).

  3. 3

    Check the drive's environment for excessive heat, dust, or potential sources of strong electromagnetic interference (e.g., arc welders).

  4. 4

    Perform a factory reset of drive parameters (e.g., P14-22 or P14-23) and carefully re-enter essential motor and application parameters.

  5. 5

    If the fault persists, replacement of the control card or the entire drive unit may be necessary after consulting the manufacturer's diagnostic guides.

Browse all codes in this manual (40)
Verified technical data. Last updated: April 2026

Related Faults

10Motor overload temperature11Motor thermistor overtemperature13Overcurrent
Source: Danfoss VLT HVAC Basic FC 101
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