SC Fault Code 5 - AirVolution/AirLegacy Troubleshooting (Public)

A SC fault (fault code 5 on the touchscreen) is a short circuit fault. The VFD has detected a short circuit on the output. Below are some possible causes.

1. The motor cable is not properly wired to the VFD motor terminals. Ensure that the motor cable is landed on the correct terminals. Ensure that the cable is stripped properly so that the terminal is not biting on any insulation. Ensure that there are no frayed ends of wires touching other wires.

2. A wire is loose or missing on the output side of the VFD. Confirm that the wires are snug in the VFD motor output terminals and that they are properly tied together inside the motor. Ensure that there are no frayed ends of wires touching other wires.

3. The motor cable is incorrect. It could be damaged, exceed the maximum allowable length, or it is a cable sourced from a 3rd party that does not meet the necessary specifications. Our cable must be used with no additions or substitutions in order to ensure the proper operation of the fan and maintain the warranty.

4. The motor is miswired. This is most commonly caused by not rewiring motors from high voltage to low voltage. Verify that the motor is properly wired for high voltage (480V) or low voltage (240V) depending on your application. Ensure that the cable is stripped properly so that the terminal is not biting on any insulation.

5. There is a VFD programming issue. Contact MacroAir Technical Support to verify the VFD programming.

6. The motor may be damaged. Operate the VFD without the motor connected to the VFD. If the fault persists, a replacement motor may be necessary. Contact MacroAir Technical Support for further assistance.

The motor windings can also be checked by reading the resistance. Take resistance readings both at the end of the motor cable in the control panel and also at the motor after disconnecting the motor cable. The ohm readings should be fairly consistent in both spots and consistent with each other. 

• If the ohms are good at the motor, but inconsistent at the end of the cable, the cable may be the issue.
• If the ohms are not good at the motor, the motor may be the issue.