This document is a service manual for Willis Air Conditioning units, covering models WAM09MH27S, WAM12MH25S, WAM18MH21S, and WAM24MH21S. It provides comprehensive information for installation, operation, troubleshooting, and maintenance of these air conditioning systems.

Function Description

The Willis Air Conditioning units are designed for both cooling and heating, with specific models offering different capacities. The system comprises an indoor unit, an outdoor unit, and a remote controller for user interaction. The indoor unit, also referred to as the evaporator, handles the air processing within the room, while the outdoor unit, containing the compressor and condenser, manages the heat exchange with the external environment. The system utilizes a refrigerant cycle, including a 3-way valve, 2-way valve, accumulator, strainer, and electron expansion valve, to achieve cooling and heating.

The units feature various operational modes:

Cooling Mode: The compressor and outdoor fan operate, and the indoor fan runs at a set speed. The system adjusts its operation based on indoor and outdoor ambient temperatures to maintain the desired cooling.
Heating Mode: The compressor and outdoor fan operate, and the indoor fan runs in cold-air prevention mode. Similar to cooling, operation is adjusted based on ambient temperatures.
Dry Mode: The unit operates to reduce humidity in the room, with the compressor and outdoor fan running, and the indoor fan at a low speed.
Fan Mode: Only the indoor fan operates at a preset speed, while the compressor, outdoor fan, and 4-way valve are turned off.
AUTO Mode: The system automatically selects between Cool, Heat, or Fan modes based on the ambient temperature.
Sleep Mode: This mode adjusts the temperature settings over time to ensure comfortable sleep, with different sleep curves for cooling and heating.
X-FAN Function: After turning off the unit in COOL or DRY mode, the indoor fan continues to operate for 10 minutes to dry the indoor unit and prevent mold.
Turbo Function: Allows the unit to quickly reach the desired temperature by running at super-high fan speed.
Quiet Mode: Reduces operational noise, with fan speed adjusted to the lowest setting.
8℃ Heating Function: Maintains a minimum temperature of 8℃ (46℉) in heating mode, useful for preventing freezing in unoccupied spaces.
Energy-saving Function: Optimizes operation in cooling mode to reduce energy consumption.
Defrosting Function: Automatically initiated in heating mode when conditions require, to remove frost from the outdoor unit.

Important Technical Specifications

The manual provides detailed specifications for each model, including:

Indoor Unit (WAM09MH27S / WAM12MH25S / WAM18MH21S / WAM24MH21S):

Power Supply: V~/Hz/Phase (e.g., 208/230V, 60Hz, 1 Phase).
Cooling Capacity (Min-Max): Btu/h (e.g., 9000(3500-9600) for WAM09MH27S).
Heating Capacity (Min-Max): Btu/h (e.g., 9600(2200-11200) for WAM09MH27S).
Cooling Power Input (Min-Max): W (e.g., 800(100-1200) for WAM09MH27S).
Heating Power Input (Min-Max): W (e.g., 650(100-1250) for WAM09MH27S).
Cooling Current Input: A (e.g., 5.7 for WAM09MH27S).
Heating Current Input: A (e.g., 4.7 for WAM09MH27S).
Rated Current: A (e.g., 9 for WAM09MH27S).
Air Flow Volume: CFM (e.g., 1300 for WAM09MH27S).
Dehumidifying Volume: Pint/h (e.g., 2.96 for WAM09MH27S).
EER (Btu/h)/W: (e.g., 14.5 for WAM09MH27S).
COP (Btu/h)/W: (e.g., 13 for WAM09MH27S).
SEER: (e.g., 27 for WAM09MH27S).
HSPF: (e.g., 27 for WAM09MH27S).
Application Area: m² (e.g., 16-24 for WAM09MH27S).
Indoor Unit Fan Type: Cross-flow.
Indoor Unit Fan Diameter: inch (e.g., Φ3.86X3/50 for WAM09MH27S).
Length (DXL): inch (e.g., Φ3.86X3/50 for WAM09MH27S).
Cooling Speed (Max~Min): r/min (e.g., 1400/1050/1000/900/800/700/500 for WAM09MH27S).
Heating Speed (Max~Min): r/min (e.g., 1400/1150/1080/1030/980/900/850 for WAM09MH27S).
Evaporator Coil Length (LXDXW): inch (e.g., 26.1X5.0X1X10.2/5 for WAM09MH27S).
Sound Pressure Level (Max~Min): dB(A) (e.g., 42/38/36/34/30/26/23 for WAM09MH27S).
Dimension (WXHXD): inch (e.g., 34.1X11.5X8.2 for WAM09MH27S).
Indoor Unit Net Weight: lb (e.g., 24.3 for WAM09MH27S).

Outdoor Unit (WAM09MH27S / WAM12MH25S / WAM18MH21S / WAM24MH21S):

Compressor Type: Rotary.
Compressor RLA: A (e.g., 3.8 for WAM09MH27S).
Compressor LRA: A (e.g., 13.8 for WAM09MH27S).
Compressor Power Input: W (e.g., 860 for WAM09MH27S).
Refrigerant: R410A.
Refrigerant Charge: oz (e.g., 45.9 for WAM09MH27S).
Condenser Coil Length (LXDXW): inch (e.g., 30.0X2.1/5X21.7/10 for WAM09MH27S).
Outdoor Unit Fan Motor Speed: rpm (e.g., 600/750/850 for WAM09MH27S).
Outdoor Unit Air Flow Volume: CFM (e.g., 1177 for WAM09MH27S).
Outdoor Unit Fan Type: Axial-flow.
Dimension (WXHXD): inch (e.g., 35.4X23.5X11.9 for WAM09MH27S).
Outdoor Unit Net Weight: lb (e.g., 86.0 for WAM09MH27S).
Max Distance Height: ft (e.g., 32.8 for WAM09MH27S).
Max Distance Length: ft (e.g., 49.2 for WAM09MH27S).

The manual also includes operation characteristic curves for cooling and heating, capacity variation ratios, and noise criteria curves for both indoor and outdoor units, providing insights into performance under different conditions.

Usage Features

The air conditioning units are designed for user-friendly operation via a remote controller. Key usage features include:

ON/OFF Button: Powers the unit on or off.
MODE Button: Cycles through Auto, Cool, Dry, Fan, and Heat modes.
FAN Button: Adjusts fan speed (Auto, Low, Medium-low, Medium, Medium-high, High).
TEMP Buttons (+/-): Adjusts the desired temperature.
CLOCK Button: Sets the current time.
LIGHT Button: Controls the display panel light.
SWING UP AND DOWN / LEFT AND RIGHT Buttons: Controls the direction of the air louvers for optimal air distribution.
TIMER ON/OFF: Schedules the unit to turn on or off at a specific time.
I FEEL Function: Allows the remote controller to sense the ambient temperature and send it to the main unit for more precise control.
Health and Cold Plasma Function: Activates functions for improved air quality.
Static Dedusting Function: Helps remove dust from the air.
Fahrenheit Display: Option to display temperature in Fahrenheit.
Memory Function: Retains previous settings (mode, swing, light, set temperature, fan speed) after a power interruption.
Locked Protection: Prevents unauthorized changes to settings.

The remote controller is universal and may have buttons for functions not available on all units. The manual provides clear instructions on how to use each button and what to expect from the unit's display.

Maintenance Features

The service manual emphasizes safety precautions for installation, start-up, and servicing, highlighting the need for trained and qualified personnel. It also outlines several maintenance-related features and checks:

Pre-inspection and Repair Precautions: Details safety measures, including disconnecting power, locking out switches, wearing safety gear, and avoiding contact with refrigerant and hot components.
Troubleshooting Guide: A comprehensive section with flowcharts and tables to diagnose common malfunctions based on symptoms (e.g., unit not starting, fan not running, abnormal sounds, leakage) and flashing LED codes.
Error Codes: Provides a table of malfunction names, display codes (Nixie Tube, LED Lamp for Operation, Cooling, Heating, Yellow LED, Red LED), and possible causes for both indoor and outdoor units.
Temperature Sensor Resistance Tables: Includes resistance values for indoor and outdoor temperature sensors at various temperatures, useful for diagnosing sensor malfunctions.
Cleaning and Maintenance: Instructions for cleaning the air filter and other components.
Removal Procedures: Detailed step-by-step instructions with illustrations for disassembling both indoor and outdoor units, including components like the front panel, filters, guide louvers, electric box, evaporator, fan blades, compressor, and valves. This is crucial for component replacement and in-depth servicing.
Electrical Data and Wiring Diagrams: Provides electrical specifications and schematic diagrams for both indoor and outdoor units, essential for electrical troubleshooting and wiring checks.
Installation Checks: A checklist to ensure proper installation, covering aspects like secure fixing, refrigerant leakage, thermal insulation, water drainage, voltage, electrical wiring, grounding, and pipe connections.

The manual stresses the importance of regular maintenance and proper handling to ensure the longevity and safe operation of the air conditioning units. It also notes that Willis reserves the right to modify product specifications and appearance without prior notice for continuous improvement.

Willis WAM09MH27S - Page 4

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