Delta VFD-F Drive Fault Codes List

Access the complete reference guide for the legacy Delta VFD-F fan and pump drive. Learn to diagnose PID feedback errors, sleep mode issues, and reset faults.

This guide provides the most updated reference for 2026 to help you maintain these aging HVAC drives and troubleshoot air/water flow issues.

Delta VFD-F Fault Codes Reference Table

 

Fault Code and Meaning
Cause and Remedy
oc
Over Current
Cause:

The AC drive detects an abnormal increase in current.



Remedy:


  1. Check whether the motor’s horsepower corresponds to the AC drive output power.

  2. Check the wiring connections between the AC drive and motor for possible short circuits.

  3. Increase the Acceleration time.

  4. Check for possible excessive loading conditions at the motor.

  5. If there are any abnormal conditions when operating the AC drive after short-circuit being removed, it should be sent back to manufacturer.
ou
Over Voltage
Cause:

The AC drive detects that the DC bus voltage has exceeded its maximum allowable value.



Remedy:


  1. Check whether the input voltage falls within the rated AC drive input voltage.

  2. Check for possible voltage transients.

  3. Bus over-voltage may also be caused by motor regeneration. Either increase the decel time or add an optional brake resistor.

  4. Check whether the required brake power is within the specified limits.
oH
Over Heat
Cause:

The AC drive temperature sensor detects excessive heat.



Remedy:


  1. Ensure that the ambient temperature falls within the specified temperature range.

  2. Make sure that the ventilation holes are not obstructed.

  3. Remove any foreign objects on the heatsinks and check for possible dirty heat sink fins.

  4. Provide enough spacing for adequate ventilation.
Lu
Low Voltage
Cause:

The AC drive detects that the DC bus voltage has fallen below its minimum value.



Remedy:


  • Check whether the input voltage falls within the rated AC drive’s input voltage.
oL
Over Load
Cause:

The AC drive detects excessive drive output current.

Note: The AC drive can withstand up to 150% of the rated current for a maximum of 60 seconds.



Remedy:


  1. Check whether the motor is overloaded.

  2. Reduce torque compensation setting as set in Pr.7-02.

  3. Increase the AC drive’s output capacity.
oL1
Internal electronic overload trip
Cause:

Internal electronic overload trip.



Remedy:


  1. Check for possible motor overload.

  2. Check electronic thermal overload setting.

  3. Increase motor capacity.

  4. Reduce the current level so that the drive output current does not exceed the value set by the Motor Rated Current Pr.7-00.
oL2
Motor Overload
Cause:

Motor overload. Check the parameter settings (Pr.6-03 to Pr.6-05).



Remedy:


  1. Reduce the motor load.

  2. Adjust the over-torque detection setting to an appropriate setting (Pr.06-03 to Pr.06-05).
HPF1
GFF hardware error
Cause:

GFF hardware error.



Remedy:


  • Return to the factory.
HPF2
CC (Current Clamp)
Cause:

CC (Current Clamp) error.



Remedy:


  • Return to the factory.
HPF3
OC hardware error
Cause:

OC hardware error.



Remedy:


  • Return to the factory.

How to Read VFD-F Faults via Keypad & VFDSoft

The VFD-F is designed for autonomous PID control. Troubleshooting in 2026 often involves checking why the drive isn’t “waking up” or why it tripped during high demand:

  • The PU06 Keypad: The standard keypad is your primary diagnostic tool.
    • PID Feedback: By pressing the Mode button, you can toggle the display to show the “b” value (PID Feedback signal). If the drive trips on a process error, checking this value tells you if your pressure transducer (4-20mA) has failed.
  • VFDSoft (Legacy PC Tool): Connect via the RS-485 port. Use the Status Monitor to check the DC Bus Voltage. Since these drives operate fans (high inertia), a failing internal capacitor bank often manifests as “Low Voltage” (Lv) faults during startup.
  • Sleep/Wake Status: Sometimes the drive isn’t faulted, but simply “Sleeping.” If the display is blinking or shows a specific frequency (like 0.0 Hz) without running, verify the Sleep Frequency parameters (Group 10) before assuming a hardware failure.

Frequently Asked Questions (FAQ)

Q: Why does my VFD-F trip on “oH” (Overheat) frequently?

A: This is common in HVAC rooftop units.

  • Check if the heatsink fins are clogged with dust or pollen.
  • Ensure the cabinet cooling fan is operational.
  • If the “oH” fault occurs instantly on a cold morning, the internal temperature sensor has likely failed.

Q: How do I reset a Delta VFD-F fault?

A:

  1. Press the RESET key on the keypad.
  2. Trigger the External Reset input (M0-M5 configured to 05).
  3. Power cycle the drive. Note: If the fault is related to “PID Loss” (feedback wire broken), the fault will return immediately until the sensor is fixed.

Q: Can I replace the VFD-F with a CP2000?

A: Yes. The Delta CP2000 is the direct successor. It offers built-in BACnet (which the VFD-F lacks), Fire Mode, and better energy efficiency. Parameter migration is manual, but the wiring logic is very similar.

 

 

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