Overview

FAN Mode operation is now available on certain VRF indoor units. This functionality was added following a software update that introduced inverse logic control for external inputs.
This change allows the indoor fan to operate independently of heating or cooling mode when enabled.

Background

Historically, FAN Mode has been restricted on VRF indoor units.
Fujitsu General advised against fan-only operation due to the potential for residual refrigerant flow through the indoor coil.
In systems where other connected units are in operation, a small amount of refrigerant may still pass through coils, resulting in slight heating or cooling even when only fan mode is selected.

Applicability

This function is available only on indoor units equipped with updated control board software.
Please refer to the attached serial number list to confirm compatibility.

Procedure – Enabling FAN Mode

  1. Access the indoor unit’s Function Setting Mode.

  2. Locate Function 99.

  3. Change the setting from 00 (Disabled) to 01 (Enabled).

  4. Once changed, FAN Mode will appear as an available option on the remote controller.

Important Notes

  • FAN Mode is disabled by default to prevent unwanted temperature effects caused by residual refrigerant circulation.

  • When activated, FAN Mode allows for air circulation only, but depending on system conditions, a minor temperature variance may be noticed.

  • This update does not affect normal heating or cooling operation.

  • Only perform this setting change if the client specifically requires fan-only functionality.

Technical Support Guidance

  • Confirm indoor unit software version matches the list of applicable serial numbers before enabling FAN Mode.

  • Inform the end user of possible light airflow temperature changes when FAN Mode is active.

  • For systems without the required software version, FAN Mode will not appear as a selectable option even if Function 99 is changed.