29

Heatsink Over Temperature

Danfoss · VLT HVAC Drive FC 102

What does 29 mean?

The temperature of the drive's heatsink has exceeded its safe operating limit. This is a critical indicator of insufficient cooling for the drive's power components, which can cause component damage and premature drive failure if not addressed.

Common Causes

  • Insufficient airflow around the drive due to blocked ventilation openings or inadequate cabinet spacing (e.g., less than 100mm clearance).
  • Failure of the drive's internal or external cooling fan(s) (e.g., bearings seized, motor winding open circuit) reducing heat dissipation.
  • Ambient temperature inside the control cabinet exceeding the drive's maximum operating limit (e.g., above 40°C or 104°F).
  • Accumulation of dust, dirt, or debris on the heatsink fins, creating an insulating layer that prevents efficient heat transfer.
  • Drive operating continuously at or above its nominal output current (P0-01, Motor Current) without sufficient duty cycle reduction or oversizing for the application.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Verify that all cooling fans (internal and external) are operating at rated speed; measure fan input voltage (e.g., 24VDC) if accessible.

  2. 2

    2. De-energize the drive and use compressed air to thoroughly clean all heatsink fins and ventilation openings, removing any dust or debris.

  3. 3

    3. Measure the ambient temperature inside the control cabinet using a calibrated thermometer and ensure it remains within the drive's specified operating range (e.g., 0-40°C).

  4. 4

    4. Monitor the drive's output current (P0-01, Motor Current) and compare it against the drive's nominal current rating and parameter P6-02 (Rated Motor Current) for sustained overloading.

  5. 5

    5. Confirm adequate clearance around the drive within the control cabinet (e.g., minimum 100mm above and below) to ensure unrestricted airflow.

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Verified technical data. Last updated: March 2026

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Source: Danfoss VLT HVAC Drive FC 102