Fujitsu ASU18CL Service Manual

The Fujitsu ASU18CL is a high-efficiency split-type air conditioning unit with advanced inverter technology, designed for residential and light commercial applications. This service manual provides comprehensive technical information for qualified service technicians, including safety precautions, technical specifications, installation procedures, maintenance guidelines, troubleshooting, and repair instructions.

1. Safety Precautions 2. Technical Specifications 3. Installation Procedures 4. Electrical Components 5. Refrigerant System 6. Control System 7. Maintenance Procedures 8. Troubleshooting Guide 9. Error Codes 10. Parts List 11. Wiring Diagrams

Safety Precautions

Before servicing, read all safety instructions carefully. Only qualified technicians should perform service operations.

Hazard Type	Precaution
Electrical Shock	Disconnect power before servicing; use insulated tools
Refrigerant	Wear protective gloves and goggles when handling refrigerant
High Pressure	Release pressure before opening refrigerant system
Moving Parts	Ensure all moving parts are stopped before servicing
Hot Surfaces	Allow components to cool before touching
Chemical Exposure	Use proper ventilation when working with chemicals

Technical Specifications

Model: ASU18CL
Cooling Capacity: 18,000 BTU/h
Power Supply: 208-230V, 60Hz, 1Phase
Refrigerant: R410A
Operating Range: Cooling: 14°F to 115°F
Sound Level: Indoor: 26 dB(A), Outdoor: 52 dB(A)
Dimensions: Indoor: 31.5" x 11.8" x 8.7", Outdoor: 33.1" x 25.6" x 13.0"
Weight: Indoor: 22 lbs, Outdoor: 121 lbs

Installation Procedures

Proper installation is critical for optimal performance and safety.

Select installation location: Ensure adequate clearance and proper drainage
Mount indoor unit: Use provided mounting plate and ensure level installation
Install outdoor unit: Place on stable surface with proper vibration isolation
Connect refrigerant piping: Use flare connections and proper torque
Connect electrical wiring: Follow wiring diagram and local codes
Vacuum and charge system: Evacuate to 500 microns, charge with R410A

WARNING! Incorrect installation may cause equipment damage, personal injury, or void warranty.

Electrical Components

Major electrical components and their functions.

Component	Function	Specifications
Compressor	DC Inverter type	Variable speed control
Indoor Fan Motor	DC motor	4-speed control
Outdoor Fan Motor	DC motor	Variable speed
PCB Main Board	System control	Microprocessor based
Inverter PCB	Compressor control	IPM module
Thermistors	Temperature sensing	Multiple locations

Refrigerant System

Refrigerant circuit components and service procedures.

Refrigerant Type: R410A (HFC)
Charge Amount: Refer to unit nameplate
Service Ports: High and low pressure ports
Oil Type: POE oil
Leak Testing: Use electronic leak detector or bubble solution
Recovery: Use approved recovery equipment

CAUTION! R410A operates at higher pressures than R22. Use dedicated R410A tools and gauges.

Control System

Advanced control features and operation modes.

Inverter Control: Variable compressor speed for precise temperature control
Operation Modes: Cool, Heat, Dry, Fan, Auto
Fan Speeds: Auto, Low, Medium, High, Quiet
Timer Functions: On/Off timer, weekly programming
Remote Control: Wireless remote with LCD display
Self-Diagnosis: Automatic fault detection and display

Maintenance Procedures

Routine maintenance for optimal performance and longevity.

Air Filters: Clean every 2 weeks, replace every 6 months
Heat Exchangers: Clean annually with soft brush
Drain Pan: Clean and check for proper drainage
Fan Blades: Clean and check balance
Electrical Connections: Check for tightness and corrosion
Refrigerant Charge: Verify proper charge and check for leaks

Troubleshooting Guide

Common problems and solutions.

Symptom	Possible Cause	Corrective Action
Unit not starting	Power supply, fuse, thermostat	Check voltage, replace fuse, verify thermostat settings
Poor cooling	Dirty filters, low refrigerant	Clean filters, check refrigerant charge
Noisy operation	Loose parts, fan issues	Tighten components, check fan motor and blades
Water leakage	Clogged drain, improper slope	Clear drain line, ensure proper unit leveling
Error code display	System fault	Refer to error code section for specific diagnosis

Error Codes

Self-diagnosis error codes and their meanings.

Code	Description	Action Required
E0	Protection of outdoor PCB	Check outdoor unit PCB and connections
E1	Indoor/outdoor communication error	Check wiring between indoor and outdoor units
E3	High pressure protection	Check refrigerant charge, condenser cleanliness
E4	Low pressure protection	Check for refrigerant leaks, proper charge
E5	Compressor overload	Check compressor, power supply, refrigerant
E6	Communication error	Check indoor PCB and wiring

Parts List

Major replacement parts and their part numbers.

Compressor: PART-COMP-ASU18CL
Indoor Fan Motor: PART-FAN-IN-18CL
Outdoor Fan Motor: PART-FAN-OUT-18CL
Main PCB Indoor: PART-PCB-IN-18CL
Inverter PCB: PART-INV-18CL
Thermistor Set: PART-THERM-18CL
Capacitor: PART-CAP-18CL
Remote Control: PART-RC-18CL

Wiring Diagrams

Complete electrical wiring schematics for indoor and outdoor units.

Indoor Unit Wiring: Power supply, control wiring, fan motor connections, thermistor locations

Outdoor Unit Wiring: Compressor connections, fan motor, inverter PCB, protection devices

Inter-unit Wiring: Communication wiring between indoor and outdoor units

Note: Always disconnect power before working on electrical components. Refer to detailed wiring diagrams included with unit documentation.