Danfoss FC302 AL-96 — What It Means
AL-96 does not exist in official Danfoss FC302 documentation. The FC302 series uses alarm codes numbered 1 through 72, and no manufacturer spec sheet or alarm list includes an AL-96 code. This is likely a misread display, a typo, or confusion with a different VFD brand or model. The closest valid internal fault on the FC302 is Alarm 38, which signals an internal hardware or software problem. Alarm 38 often includes a sub-code (such as 38-5376 or higher) that specifies the exact component or circuit at fault.
If your display shows something that looks like AL-96, write down the exact alphanumeric string and compare it to the alarm list in your FC302 operating manual. Check parameter 15-32 to see the extended alarm detail and sub-code. If the display truly shows a code not listed in Danfoss documentation, the control board may be corrupted or the display itself may be damaged.
Before You Replace Anything
Technicians sometimes replace the entire drive when a loose control wire or noise interference is the real problem. Power-cycle the VFD and check all control wiring and grounding connections before ordering any boards.
Common Causes
- Misread or mistyped alarm code (~40%) The display was read incorrectly, or the code was transcribed with a typo, since AL-96 is not a valid Danfoss FC302 alarm.
- Control board memory or firmware corruption (~25%) The control PCB has experienced a memory error or firmware glitch that displays an invalid code or triggers Alarm 38.
- Loose or damaged control wiring (~15%) Connections to the I/O card or keypad are loose, corroded, or pinched, causing communication errors that may show as Alarm 38.
- Electrical noise interference (~10%) Power cables or motor leads are routed too close to control wiring, inducing noise that corrupts internal signals and triggers Alarm 38.
- Overheating due to blocked cooling (~5%) Fans are failed or vents are clogged, causing the drive to overheat and trip Alarm 38 with a thermal sub-code.
- Failed DC-link capacitor or IGBT module (~5%) A shorted power component on the inverter or rectifier board generates an internal fault that may appear as Alarm 38.
Quick Diagnosis
Answer these to narrow it down fast.
Does the display show exactly 'AL-96' or does it show 'Alarm 38' with a sub-code?
No: If it truly shows AL-96, photograph the display and contact Danfoss support, as this is not a documented code.
Does the alarm clear after a full power cycle (AC input off for 60 seconds)?
No: A persistent fault indicates a hardware failure on the control board, power board, or IGBT module. Call a VFD technician.
Do all cooling fans run when the drive is powered up?
No: Replace or repair the failed fan, clean all vents and heatsinks, then reset and retest.
Step-by-Step Fix
- Write down the exact alarm code displayed on the keypad, including any sub-code (for example, Alarm 38-5376), and photograph the screen if possible.
- Power cycle the drive by switching off the AC input disconnect, waiting 60 seconds for capacitors to discharge, then switching back on and attempting a restart.
- Check parameter 15-32 on the keypad to view the extended alarm detail and any sub-code that identifies the specific internal fault.
- Inspect all control wiring to the I/O card, keypad, and external control devices. Tighten terminals and verify control wiring is separated from power and motor cables by at least 300 mm.
- Verify cooling fans operate and that all vents, filters, and heatsinks are clean. Replace any failed fans and clear any obstructions.
- Run an unloaded test by disconnecting the motor and attempting to run the drive in local mode. If the alarm persists with no load, the fault is internal to the drive.
- Contact Danfoss technical support with the exact alarm code, drive serial number, and parameter 15-32 sub-code. If hardware failure is confirmed, arrange for professional repair or board replacement.
Parts Often Needed
| Part | Notes |
|---|---|
| Danfoss FC302 control PCB (I/O card) | Amazon | Order by drive frame size and firmware version; verify part number with Danfoss before purchase. |
| Danfoss FC302 power board assembly | Amazon | Includes rectifier, DC-link capacitors, and inverter; required if IGBT or capacitor failure is confirmed. |
| FC302 cooling fan module | Amazon | Match frame size and voltage rating; some larger frames use multiple fans. |
When to Call a Pro
Call a qualified VFD technician or authorized Danfoss service partner if the alarm persists after a power cycle, if the exact code does not appear in the FC302 alarm list, or if parameter 15-32 points to a hardware fault such as a failed control board, IGBT module, or DC-link capacitor. Professional diagnostics require high-voltage safety equipment, firmware tools, and component-level testing. Do not open the drive enclosure while power is connected, and do not attempt to replace power boards or IGBTs without proper lockout, discharge procedures, and ESD protection. If the drive is under warranty or part of a critical process, contact Danfoss support directly to avoid voiding coverage or damaging the unit.
Rough cost: A pro service call runs about $200-600.