Overview

This document outlines the standard diagnostic and component testing procedures for Fujitsu air conditioning systems. It provides field technicians with the correct multimeter test methods, expected readings, and safety precautions for both indoor and outdoor unit components.

Contents

The guide covers testing procedures for all primary electrical and electronic components, including:

  • System Communication Tests – Verifying indoor-to-outdoor and remote control signal integrity.

  • Power Conversion Circuits – Testing of Diode Bridges, Active Filters (ACTPM), and Intelligent Power Modules (IPM).

  • Fan Motors – Procedures for DC Brushless Fan Motor diode and voltage tests.

  • Thermistors – Step-by-step checks with power on/off and correlation charts for resistance vs. temperature.

  • Pressure Transducers – Voltage-based pressure verification and diode test values.

  • Electronic Expansion Valves (EEV) – Resistance tests for 5-wire, 6-wire, and high-resistance coils.

  • Signal Verification – Expected voltage ranges for 3-wire remotes and DC serial communication between units.

  • Test Run Procedures – Operation initiation via the outdoor LED display when controller access is unavailable.

Measurement Standards

All test procedures specify:

  • Multimeter mode (Diode, Resistance, or Voltage).

  • Probe polarity (Black/Red lead positions).

  • Expected voltage or resistance values under normal conditions.

  • Visual indicators (LEDs, board labels, wire colours) for test accuracy.

For instance:

  • ACTPM module: 720–900 kΩ between “+” and “P” terminals

    Fujitsu Component Testing (2)

    .

  • IPM (Transistor Board): 0.4 V diode drop across U/V/W to N and 0.7–0.9 V between P and N

    Fujitsu Component Testing (2)

    .

  • Fan Motors: 330–380 V DC (Red–Black) and 15 V DC (White–Black) supply expected

Application

This guide is designed for use by qualified HVAC technicians during:

  • Fault diagnosis and verification after error codes.

  • Component replacement verification.

  • Post-service quality assurance and commissioning checks.

Always follow isolation procedures and verify DC voltage discharge prior to testing.

Supplementary Tools

For enhanced troubleshooting, technicians are encouraged to use the Fujitsu M Technician App, which provides:

  • Digital access to error codes, thermistor conversion charts, and test voltage calculators

  • Documentation for VRF and wireless adaptor fault-finding.