Introduction
This manual provides instructions for the safe and efficient operation of your AIRPLUS Humidifier, Model USAPS40A. Please read this manual thoroughly before use and retain it for future reference.
Important Safety Instructions
- Always place the humidifier on a firm, flat, water-resistant surface.
- Do not place the humidifier near heat sources or in direct sunlight.
- Keep out of reach of children and pets.
- Unplug the unit before filling, cleaning, or moving.
- Do not immerse the base unit in water or other liquids.
- Use only clean, cool tap water. Distilled water is recommended to prevent mineral buildup.
- Do not add essential oils directly into the water tank. Use the designated aroma box.
- Ensure the mist outlet is not blocked.
- If the unit emits an unusual smell or sound, discontinue use immediately and unplug.
Product Overview
The AIRPLUS Humidifier (Model USAPS40A) is a cool mist ultrasonic humidifier designed for home use. It features a 4-liter top-filling water tank, adjustable mist levels, an aroma box for essential oils, and an automatic shut-off function.

Image: The AIRPLUS Humidifier demonstrating its large mist output, designed to moisturize the skin and quickly improve space humidity.
Key Features:
- Top-Filling Design: Easy water refilling without removing the tank.
- 4-Liter Water Tank: Provides up to 60 hours of continuous operation.
- Adjustable Mist Levels: Three mist output settings (Low, Medium, High).
- Aroma Box: Integrated tray for essential oils.
- Automatic Shut-Off: Unit turns off when water level is low or tank is removed.
- Quiet Operation: Operates at approximately 35dB.
Setup
- Unpack the Humidifier: Carefully remove all packaging materials and place the humidifier on a flat, stable surface.
- Remove the Top Cover: Lift the top cover of the humidifier.
- Fill the Water Tank: Pour clean, cool tap water directly into the water tank. Do not fill past the MAX line. Distilled water is recommended to minimize mineral buildup.

Image: Demonstrates the convenient top-filling design, showing water being poured directly into the tank after lifting the lid.
- Replace the Top Cover: Securely place the top cover back onto the humidifier.
- Connect to Power: Plug the power cord into a standard electrical outlet.
Operating Instructions
- Power On/Off: Press the Power button (circle icon) to turn the humidifier ON or OFF. The power indicator light will illuminate.
- Adjust Mist Level: Press the Mist Level button (water drop icon) repeatedly to cycle through Low (L), Medium (M), and High (H) mist output settings. Corresponding indicator lights will show the selected level.
- Night Light Function: Press the Light button (light bulb icon) to turn the night light ON or OFF. The light provides a soft, warm glow.
- Using Essential Oils:
- Locate the aroma box tray at the bottom of the humidifier.
- Pull out the tray and add a few drops of your preferred essential oil onto the cotton pad.
- Slide the tray back into place. The mist will carry the fragrance into the air.
Maintenance
Regular cleaning is essential for optimal performance and hygiene.
- Daily Maintenance:
- Unplug the humidifier.
- Empty any remaining water from the tank and base.
- Rinse the water tank and base with fresh water.
- Wipe all surfaces dry with a clean cloth.
- Weekly Cleaning (Descaling):
- Unplug the humidifier and empty all water.
- Pour 1 cup of white vinegar into the water tank and base.
- Let it soak for 30 minutes to an hour to loosen mineral buildup.
- Use a soft brush or cloth to clean the inside of the tank and the ultrasonic nebulizer.

Image: The wide opening of the water tank, highlighting the large caliber design for easy and thorough cleaning.
- Rinse thoroughly with clean water until the vinegar smell is gone.
- Dry all parts completely before reassembling or storing.
- Aroma Box Cleaning:
- Remove the aroma box tray.
- Replace the cotton pad if it is discolored or hardened.
- Clean the tray with a mild detergent and rinse thoroughly.
Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No mist output | No water in tank / Tank not properly seated / Power not connected | Fill water tank / Re-seat tank correctly / Check power connection |
| Weak mist output | Mineral buildup on nebulizer / Low mist setting | Clean nebulizer with vinegar solution / Increase mist level |
| Unusual noise | Unit not on a flat surface / Water level too low | Place on flat surface / Refill water tank |
| Water leakage | Tank not properly sealed / Overfilled tank | Ensure tank lid is secure / Do not overfill past MAX line |
Specifications
- Model: USAPS40A
- Brand: AIRPLUS
- Capacity: 4 Liters (1.06 Gallons)
- Operation Mode: Ultrasonic Cool Mist
- Mist Output: Up to 220 ml/h
- Runtime: Up to 60 hours per refill
- Coverage Area: Up to 450 sq ft
- Noise Level: Approximately 35dB
- Dimensions: 6.22"D x 6.22"W x 13.8"H
- Weight: 4.11 pounds
- Voltage: 115 Volts
- Wattage: 28 Watts
- Special Features: 3 Mist Output Levels, Auto Shut-Off, Large Water Tank, Aroma Box
Warranty and Support
For warranty information or technical support, please refer to the contact details provided with your purchase or visit the official AIRPLUS website. Keep your purchase receipt as proof of purchase.
Online Support: Visit the AIRPLUS Store on Amazon





