Danfoss VLT AutomationDrive FC 302 fault A29: Heat Sink Temp
Alarm 29 on a Danfoss VLT FC 302 is Heat Sink Temp: the maximum heat sink temperature was exceeded. The alarm does not reset until the heat sink cools below a defined temperature, and the trip and reset points depend on drive power size.
Diagnose this with AI
Try Free Drive Diagnostic Upload a keypad photo, the fault history or a parameter export from your Danfoss VLT AutomationDrive FC 302. InduQT compares the evidence and suggests the next useful checks.
When it happens
- After running loaded for some time
- On hot days or with cabinet cooling problems
- Soon after start if the heat sink fan has failed
Likely causes and checks
1Heat sink fan damaged or not running
- Points to it
- Warning 23 or 24 fan fault logged; trips sooner than before.
- Check
- Cycle power and check the fan runs briefly at start-up; check fan operation (14-53 Fan Monitor supervises it).
2Dirty heat sink or blocked airflow
- Points to it
- Dusty site; filters or fins clogged; drive mounted with too little clearance.
- Check
- Inspect and clean the heat sink and check airflow clearance above and below the drive.
3Ambient temperature too high
- Points to it
- Trips cluster on hot afternoons; cabinet interior hot.
- Check
- Measure cabinet air temperature near the drive and compare with the drive’s rated ambient.
4Motor cables too long
- Points to it
- Long motor cable run; drive runs hot even at moderate load.
- Check
- Check motor cable length against the limits in the Operating Guide; Danfoss lists long cables as a cause.
Telling it apart
- Alarm 69 Power Card Temperature means the power card sensor is too hot (or too cold); Danfoss lists ambient limits, clogged filters, fan operation and the power card itself.
- Warning/Alarm 65 is the control card overtemperature; Alarm 39 Heat Sink Sensor means the sensor signal is missing, not that the heat sink is hot.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| 14-53 | Fan Monitor | Fan fault warnings 23/24; do not disable it to hide a failed fan. |
Evidence to collect
- Alarm log time and ambient temperature
- Fan warnings (23/24) in the log
- Photo of heat sink and filters
- Drive mounting clearances
- Motor cable length
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