Danfoss FC302 AL-67 Fault — What It Means
Alarm 67 on the Danfoss FC302 VFD indicates that the drive has detected a different option card (communication, I/O, or encoder module) than the one previously configured or recognized during startup. This is a configuration validation error, not a power or motor fault. The drive performs a self-check at startup and compares the expected option module ID with the actual hardware present. When these do not match, AL-67 is triggered.
The fault typically appears after an option module has been physically inserted, removed, replaced, or when the stored configuration has been corrupted by a power loss or firmware glitch. The drive will not operate normally until the hardware and software configuration are brought back into alignment.
Before You Replace Anything
Technicians sometimes replace the control card when the real issue is simply a loose or incompatible option module. Always verify the physical module is seated correctly and matches the drive’s parameter configuration before ordering control boards.
Common Causes
- Loose or improperly seated option card (~40%) Physical vibration or incomplete installation causes intermittent detection or failure to initialize during the drive’s startup self-check.
- Option module swapped without parameter update (~25%) A fieldbus or I/O module was replaced with a different type but the drive’s internal parameters still reference the old module ID.
- Power loss or firmware glitch (~15%) A sudden shutdown or brownout corrupted the stored option module configuration in the drive’s memory.
- Incorrect terminal wiring conflict (~10%) Terminal 37 or terminal 27 is active and conflicts with the option module’s expected functionality, causing detection failure.
- Non-genuine or incompatible option module (~7%) A third-party or wrong-series module lacks the correct identification firmware and the drive cannot recognize it.
- Faulty control PCB (~3%) In rare cases the drive’s control board itself fails to properly read a correctly installed and compatible option module.
Quick Diagnosis
Answer these to narrow it down fast.
Does the alarm clear after a full power-cycle (AC mains disconnected for 10 seconds)?
No: Proceed to physically inspect the option module slot and verify the module is fully seated and matches the drive parameters.
Is the installed option module the same model number as the one listed in the drive's parameter configuration?
No: The drive expects a different module. Either replace the physical module with the correct type or use Danfoss MCT 10 software to reconfigure the drive for the installed module.
Are terminals 37 or 27 wired for functions not required by your application?
No: The option module or control card is likely faulty and requires professional diagnosis with MCT 10 software or replacement.
Step-by-Step Fix
- Disconnect all power by turning off the AC mains supply and any DC-link power sources including UPS or batteries, and wait at least 10 seconds for capacitors to discharge.
- Open the drive enclosure and locate the option module slot on the control card, typically on the side or front of the FC302 unit.
- Inspect the option module physically for proper seating, bent pins, or debris in the connector, and press firmly to reseat if necessary.
- Verify the module model number matches the configuration expected by the drive, either by checking the label or using Danfoss MCT 10 software to read the current module ID.
- Power-cycle the drive by reconnecting AC mains and allowing it to complete its startup self-check, then observe whether AL-67 clears.
- Check terminal wiring to confirm terminal 37 is not connected to terminal 12 unless your application requires it, and set parameter 5-12 to [0] No function if terminal 27 is unused.
- Reconfigure or replace the module using MCT 10 software to update the drive parameters if the physical module has changed, or install the correct Danfoss-certified option module if the current one is incompatible or damaged.
Parts Often Needed
| Part | Notes |
|---|---|
| Danfoss FC302 option module (FCN, FCM, ENC, or communication module) | Amazon | Must match your application and be Danfoss-certified for the FC302 series; consult your drive’s manual for the correct model number. |
| Danfoss FC302 control PCB | Amazon | Only needed if the option module is confirmed good but the drive still fails to detect it after reseating and power-cycling. |
When to Call a Pro
Call a qualified industrial electrician or VFD technician if you are not trained to work inside variable frequency drives or if you lack access to Danfoss MCT 10 configuration software. High-voltage AC mains and DC-link capacitors present shock and arc-flash hazards. A professional can safely diagnose whether the issue is a loose module, incorrect parameter settings, or a failed control board, and can reconfigure the drive or replace components as needed. If your facility does not have a maintenance contract, expect a service call fee plus parts and labor.
Rough cost: A pro service call runs about $150-400 for service call and configuration reset, more if module replacement needed.