How to Replace an Air Purifier Filter: Complete Guide for All Brands
Replacing an air purifier filter takes about ten minutes: unplug the unit, open the access panel, remove the old filter, drop in a compatible new one, and close it back up. The real challenge is knowing which filter your model takes, how often to swap it, and what to do when the unit flashes an error or the grille won’t close. This guide covers those exact steps for Winix, Honeywell, Blueair, Levoit, Coway, and other common brands.
Before You Start
Have these items ready before you touch the purifier:
- Screwdriver set – Some front grilles are held by Phillips or Torx screws.
- New filter – Pull the model number from the sticker on your current filter or the user manual. For a Winix C535, the correct replacement is the Genuine Winix 115115 Replacement Filter A (around $32). Always verify compatibility by the part number, not just the brand name.
- Vacuum with brush attachment – Use it to clean dust off the pre-filter and inside the cabinet while you have the unit open.
- Gloves – Optional, but old filters can be heavily loaded with dust and allergens.
- Multimeter (optional) – Only necessary if the purifier won’t power on after the swap; you can check whether the power cord or internal fuse is blown.
Safety first: Unplug the unit completely. Even with the power switch off, some models keep a low standby current that can surprise you.
Stop threshold: If you notice any of these signs, do not attempt a filter swap yourself – call a qualified technician instead:
- Melted or discolored plastic around the filter compartment
- A burning smell when the unit was running
- Visible capacitor leaks (bulging or oily residue on electronic components)
- Fan blades that are cracked, loose, or scraping against the housing
These symptoms point to electrical or mechanical failure that a simple filter change won’t fix. Attempting to power on the unit in that state can cause further damage or create a fire hazard.
Step-by-Step Filter Replacement
The basic procedure is the same across brands. The differences come down to access panel design and reset sequences.
1. Unplug and Open the Access Panel
Most purifiers have a front grille or back door that slides off or hinges open. Honeywell models often use a push-button release on the side. Levoit and Coway units typically have a notch at the bottom that you pull toward you. If the panel doesn’t move, check for hidden screws or a locking latch.
Checkpoint after opening: Look at the orientation of the dirty filter before pulling it out. Note which side faces the fan (usually the pleated side). This matters when you install the new one.
2. Remove the Old Filter
Slide the old filter straight out. If it’s stuck (common after heavy use), gently rock it from side to side. Don’t shake it violently – that just launches dust back into the room.
For units with a washable pre-filter, such as many Winix models, remove the pre-filter first, then the main HEPA filter.
Realistic failure mode: If the filter frame is warped from moisture or age, it may tear when you pull. A torn filter can leave debris inside the cabinet. If that happens, vacuum out all fragments and check the fan blades for any caught fibers. Running the unit with a torn filter installed will bypass unfiltered air and can damage the motor if fibers wrap around the fan shaft.
3. Clean the Interior
Vacuum the inside of the cabinet, especially around the fan blades and the air outlet grille. Built-up lint restricts airflow and makes the new filter work harder. Use the brush attachment on crevices and corners. If you see heavy dust on the coils, carefully clean them using a vacuum cleaner with a brush attachment and a specialized condenser coil brush.
Likely cause of poor performance after replacement: Skipping this cleaning step. Dust and pet hair can block the fan inlet even with a brand-new filter installed.
4. Insert the New Filter
Slide the new filter in with the sealing gasket facing the fan. The arrow embossed on the filter frame usually points toward the fan. Press it fully into the slot until it sits flush against the back wall.
For Blueair units that use electrostatic or carbon-fiber filters, make sure the metal mesh sides align with the contact pins inside the unit.
5. Close the Panel and Plug In
Snap the grille or door back into place. If you removed screws, tighten them fingertight – overtightening can crack plastic tabs.
Plug the purifier in and turn it on. Most units run a self-check: LEDs light up, and the fan spins to full speed for a few seconds. If the filter-reset light stays on, press and hold the reset button (usually a pinhole or a long-press of the power button – check your manual).
Success check: Air flow feels noticeably stronger than before, and the filter-replace indicator (if your model has one) turns off. If the unit makes a rattling noise, the filter isn’t seated correctly; open the panel and reseat it.
Brand-Specific Notes
Winix Models
The filter compartment has a spring-loaded tab at the top. Push the tab while inserting the filter, then release it to lock. If you don’t hear a click, the filter isn’t fully seated. Winix recommends resetting the filter timer by holding the “Filter Reset” button for 3 seconds. The process for cleaning the pre-filter is similar to the steps covered in how to clean filter on therapure air purifier.
Honeywell Long-Life Models (HPA Series)
These use a permanent pre-filter that you vacuum rather than replace. The main HEPA filter sits behind a second grille secured by two thumbscrews. Don’t try to pry the grille off – unscrew it first.
Levoit Core Series
The filter tray slides out from the bottom of the unit. Some models have a small tab you press inward to release the tray. Levoit filters are directional; the foam strip must face the fan, and the frame is marked “AIR OUT” on that side.
Additional Note for Therapure Owners
If you own a Therapure model, the pre-filter cleaning method is almost identical to what you’ll find in the guide on how to clean a therapure filter. The main HEPA replacement still follows the steps above.
Where People Get Stuck
Even a straightforward swap can hit snags. Here are the three most common issues and how to fix them.
- Filter-reset light won’t turn off. Many brands require a specific reset sequence after replacement. Try unplugging the unit for 30 seconds, plugging it back in, and holding the power button (or the filter-reset pinhole) for 5–10 seconds. If the light stays on, the unit may need a hard reset – consult your manual for the exact procedure.
- Grille won’t close. The filter is too thick, or you’re trying to force an incompatible filter into the slot. Double-check the part number. Some aftermarket filters have slightly thicker frames that cause fitment problems. Stick with genuine or verified compatible brands.
- Rattling or whistling noise. This usually means the filter isn’t fully seated, or the gasket is misaligned. Open the panel, push the filter firmly into the corners, and re-close. If the noise continues, inspect the filter frame for cracks or damage.
Quick Fit Check
Before you install a new filter, run through these pass/fail checks. If any item is a “No,” stop and find a different replacement.
| Check Item | Pass (✓) | Fail (✗) |
|---|---|---|
| Part number on the filter matches your model’s manual or the old filter’s sticker | ✓ | ✗ |
| Filter dimensions (height, width, depth) are within 1/8 in. of the original | ✓ | ✗ |
| Direction arrow on the frame points toward the fan intake | ✓ | ✗ |
| Gasket or foam seal is continuous, not torn or missing | ✓ | ✗ |
| Filter is not vacuum-sealed in plastic (remove the plastic bag before install) | ✓ | ✗ |
A “No” on any check means the filter likely won’t fit properly or will leak unfiltered air around the edges. Return it and source the correct replacement.
Filter Replacement Frequency Guide
Filter life depends on usage hours, air quality in your home, and brand recommendations. The table below shows typical intervals for popular brands. Always defer to your unit’s manual if it differs.
| Brand / Model Family | Filter Type | Recommended Replacement Interval | Typical Cost (USD) |
|---|---|---|---|
| Winix (C535, 5300-2, P300) | Washable pre-filter + HEPA | Pre-filter: every 3 months (wash monthly). HEPA: every 12 months | $30–$65 |
| Honeywell (HPA300, HPA200) | HEPA + carbon pre-filter | HEPA: every 12 months. Pre-filter: replace every 3 months | $40–$70 |
| Levoit (Core 300, Core 400S) | 3-in-1 HEPA + carbon | Every 6–8 months (model-specific LED will flash) | $20–$35 |
| Coway (AP-1512HH Mighty) | Washable pre-filter + HEPA + carbon | HEPA: every 12 months. Carbon: every 6 months | $35–$50 |
| Blueair (Blue Pure 211+) | Fabric pre-filter + HEPA + carbon | HEPA: every 6 months. Pre-filter: wash every 2–3 months | $50–$70 |
Intervals shrink if you run the purifier 24/7 in a smoky or dusty home. A simple rule: if the air output feels weak or the filter looks darkly discolored, replace it early regardless of the calendar.
FAQ
Can I wash a HEPA filter and reuse it?
No – genuine HEPA media cannot be washed. Water destroys the fine fiber matting. Some models have washable pre-filters, but the main HEPA must be replaced. If you need to clean a washable pre-filter, the technique is similar to the steps in how to clean a therapure filter.
My filter-reset light came on only three months after I changed the filter. Is the new filter bad?
Usually not. The timer is set to a 12-month interval, but it counts actual runtime hours. If you run the purifier 24 hours a day, the light may trigger earlier than expected. Reset the timer as described in Step 5 and continue using the filter until you notice airflow drop or visible dirt buildup.
Do generic off-brand filters work as well as the brand’s own?
Some generics fit and perform fine, but check the gasket quality and frame thickness. A poor seal lets unfiltered air bypass the media entirely. For allergy or asthma applications, stick with brand filters or certified replacements that list the exact model numbers on the package.