Fujitsu General Australia

1. Purpose

The Fan Speed Controller (FSC) modulates condenser fan operation in response to condenser pressure or a 0–10 V signal. It provides variable fan speed for stable head pressure control and improved system efficiency, particularly under low ambient cooling conditions.

2. Components Involved

• Fan Speed Controller Box (Lüfrec / Danfoss Interface)

• Overload Protection & Contactor Assembly

• Danfoss Control Module

• 0–10 V Control Signal Wiring

• Earthing Bar

3. Mounting Location

• Mount the Fan Speed Controller vertically to allow adequate heat dissipation.

• Choose a location within the electrical panel or compressor compartment that remains accessible for service.

• On single-stage systems, the recommended position is at the bottom of the electrical panel near the compressor.

4. Electrical Wiring

a. Overload & Contactor Preparation

1. Isolate power to the unit.

2. Remove existing wiring between the bottom of the overload and the top of the contactor.

3. These terminals will be used as the connection points for the Fan Speed Controller wiring.

b. Wiring to the Fan Speed Box

• From Overload (Line In):
  Connect wiring from the bottom of the overload to the L1, L2, L3 terminals on the Fan Speed Controller.

• To Contactor (Line Out):
  Connect wiring from T1, T2, T3 terminals on the Fan Speed Controller to the bottom of the contactor.

• Earthing:
  Each connection requires an earth wire — terminate to the unit’s earth bar.

c. Speed Control Wiring

• Two control signal wires run between the Fan Speed Controller and the Danfoss module:

  • 0–10 V Output (A01) → Connects to “0.10V” terminal on FSC.

  • 0 V Common (COM) → Connects to “0V” terminal on FSC.

This allows the Danfoss controller to regulate condenser fan speed based on condensing pressure.

5. Danfoss Control Wiring

At the Danfoss Controller, verify:

• 0–10 V wire → A01 terminal

• 0 V wire → COM terminal

Ensure wiring polarity is correct to avoid signal inversion.

6. Danfoss Parameter Setup

To configure the controller for proper condenser fan modulation:

1. Enter password: 5653

2. Navigate to:

   • Parameters → Condenser → Regulation

3. Adjust:

   • Cond Setpoint in Cooling = 26.0 °C

4. Confirm and save settings.

This ensures optimal head pressure control during cooling mode.

7. Post-Installation Verification

1. Reapply power and confirm the Fan Speed Controller energizes correctly.

2. Verify correct rotation direction of condenser fans.

3. Observe fan speed modulation during system operation:

   • Fans should slow at low condensing pressure and increase as pressure rises.

4. Check that the controller housing remains cool and free from obstructions.

5. Confirm no fault LEDs are displayed on the FSC or Danfoss module.

8. Safety Notes

• Always isolate power before handling internal wiring.

• Ensure all terminals are tightened to manufacturer torque specifications.

• Use only R32/R410A-rated components where applicable.

• Maintain enclosure integrity — reseal with approved cable glands after wiring.

9. Summary of Connections

10. Functional Outcome

Once correctly installed and configured:

• The Fan Speed Controller will vary condenser fan speed proportionally to system pressure or control voltage.

• This ensures stable operation, energy savings, and extended component life under varying ambient conditions.