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electrical Issue

VFD Fault Troubleshooting

VFD faults stop your fans. Learn to diagnose common drive errors and get back to production.

Emergency: (877) 489-3727Start Diagnosis

What You're Experiencing

A variable frequency drive (VFD) controlling paint booth fan or pump motors is showing a fault code and has stopped.

Visual Signs:

  • VFD display showing fault code
  • Fault indicator LED lit
  • Motor not running
  • VFD keypad locked or unresponsive
  • Display showing abnormal values

Sound Signs:

  • Motor completely silent
  • VFD cooling fan running but motor not
  • Clicking as drive attempts to start

Safety Risks — Read Before Proceeding

critical(NFPA 33 Section 7.1)

Loss of exhaust ventilation

Action: If exhaust fan VFD faults, stop all painting operations immediately.

high(NFPA 70E)

Shock hazard

Action: VFDs contain lethal voltages. Wait for capacitors to discharge before any internal work.

Immediate Steps to Take

  1. 1

    Record fault code from VFD display

  2. 2

    Check for obvious issues: belt broken, motor locked

  3. 3

    Check input power to VFD

  4. 4

    Check for overheating (drive or motor)

  5. 5

    Look for ground fault indicators

  6. 6

    Check motor cable for damage

  7. 7

    Do NOT repeatedly reset without understanding fault

Common Causes

Here are the most likely reasons you're experiencing this problem, ranked by how often we see them.

Overcurrent Fault

common

Drive has detected excessive motor current due to overload, short circuit, or motor issue.

Overvoltage Fault

occasional

DC bus voltage too high, often from regeneration during deceleration or power surge.

Ground Fault

occasional

Insulation failure in motor or cable causing current leak to ground.

Overtemperature

occasional

Drive is overheating due to blocked cooling, high ambient, or overload.

Undervoltage

occasional

Input power has dropped below acceptable level.

Communication Fault

occasional

Drive has lost communication with controller (if network-controlled).

Interactive Diagnostic Tool

VFD Fault Diagnostic

Step 1 of 5

Is the fault code an overcurrent or overload?

If unsafe at any point: If exhaust VFD is down and cannot be quickly reset, stop painting and call WERCS at (877) 489-3727.

When to Call WERCS

While some issues can be resolved with basic troubleshooting, these situations require professional service:

  • Ground fault indicated
  • Repeated faults after reset
  • VFD damaged or smoking
  • Parameter setup needed
  • Motor testing required
  • Need VFD replacement

Priority Service Available

(877) 489-3727

Expert technicians nationwide

VFD Fault Troubleshooting FAQ

Common questions about this issue

Common codes: OC (overcurrent), OV (overvoltage), UV (undervoltage), OH (overheat), GF (ground fault), OL (overload). Each manufacturer has specific codes—check your drive manual.
Most VFDs: press STOP or RESET, or cycle power. But first understand why it faulted. Some faults (ground fault) indicate real problems that will damage equipment if you just keep resetting.
VFDs must derate at high temperatures. If ambient is >40°C (104°F), drive capacity decreases. Solutions: improve cooling, relocate to cooler area, or upsize the VFD.
Yes, but parameters must be properly configured for your motor and application. Paint booth fans often need specific accel/decel ramps and may have PLC communication. Have a qualified technician configure it.

Have a question not answered here?

Call us at (877) 489-3727

Related Problems

Vfd FaultMotor FailureExhaust Fan FailureControl Panel Fault

Related Parts & Components

Vfd DriveFan MotorMotor Starter

Can't Fix It? We Can.

WERCS expert technicians service paint booths and extraction systems nationwide. 24/7 emergency service available.

Call (877) 489-3727Request Service Quote