Airfire AP303 / AP304 Air Purifier Up to 2215 Sq. Ft.

Not sure this is your model? This filter fits the Airfire AP303 and AP304 (model code KJ3-4S), covering rooms up to 2,215 sq ft. If your unit is one of these models, this is the right replacement.

When to replace your filter

• Replace every 6–8 months under normal household use.
• When it's time, the filter-replace (HEPA) indicator flashes and keeps flashing until you replace and reset.
• Replace sooner if you notice weaker airflow, less odor removal, or you run it in heavy smoke or pollution.
• After fitting a new filter, press and hold the filter-replace button for 5 seconds to reset the indicator.

How to replace the filter

Safety first: unplug the power adapter before you start.

1. Unlock and remove the filter cover.
2. Lift out the old filter.
3. Remove the plastic wrap from the new filter. Running the purifier with the wrap still on blocks airflow and can cause it to overheat.
4. Place the new filter into the purifier.
5. Refit the cover correctly. Plug back in, then hold the filter-replace button 5 seconds to reset.

Keep your filter working between changes

• Washable pre-filter: rinse it clean, then dry it fully before reinstalling. This extends the life of the H14 HEPA behind it.
• Brush or vacuum the white side of the H14 filter monthly to clear hair and dust.
• Never wash the H14 HEPA filter with water — only the pre-filter is washable. Water damages HEPA material.

AP303 / AP304 quick specs

Troubleshooting

• Filter light still flashing after changing the filter? Press and hold the filter-replace button for 5 seconds to reset.
• Reduced airflow or odor removal? Clean or replace the washable pre-filter, or replace the H14 filter if it's due.
• Not feeling the effect? Check the filter is seated and the cover is closed, and that the intakes/outlet aren't blocked (keep 20cm clear).

Time to replace your filter?

Get the genuine H14 replacement filter for your AP303 / AP304 — free shipping within the US.

Shipping Information

• We offer free standard shipping on all AIRFIRE orders within the United States.
  
• Orders are processed within 1–2 business days.
  
• Standard shipping takes 5–7 business days depending on your location.
  
• Every order comes with a tracking number so you can follow your package in real time.
  
• Not satisfied? You can return or exchange your product within 30 days of delivery.
  

Note: Currently, AIRFIRE products are available only for U.S. customers. International shipping will be launched soon.

AIRFIRE is a brand dedicated to creating high-quality, eco-friendly products that improve everyday life. Our mission is simple: Create experiences that exceed user expectations.

When you choose AIRFIRE, you’re not just buying a product — you’re joining a community that values trust, care, and innovation.