Makes screeching noise - Bionaire BT40RC Air Purifier

The motor needs to be oiled. There are places to add oil on the ends of the motor. There may be a start capacitor that needs replaced too.

The motor has worn bushings making the motor shaft hot and swell and eventually seize. You can let it cool off and it will more than likely run again until it heats up again. The motor will have to be replaced if you want to repair it.

If the the "zapping" noise you hear is intermitant (like a Bug Zapper) it's probably dust that the air cleaner is picking up from the household air. .If that's the case, there's nothing to worry about, it's doing it's job.

If the "zapping" sound is continuous, then the unit may need cleaning, as it may be clogged with dust & lint.

Funny you should post this when you did as I just finished reassembling my S1730.
Mine was making very loud noise, arcing violently, smoking slightly and would give a good shock when you touched the plastic covers(yes dirty plastic will conduct electric current).

1. Unplug the unit
2. Take the plastic covers off, front has four screws and back has snap at bottom, both slide up when loose.
3. Wash the plastic covers
4. take the light out and clean it with windex
5. Vacuum the inside, be careful of the two corona wires
6. Find the bead on each corona wire and while turning them slight so the edges scrapes the wire, move them back and forth to scrap the white power off the wires
7. scrape the cone shape plastic that the corona wires runs into, this build up is the primary culprit of the arcing which is the noise you hear. be careful of the corona wires again. I used an exacto knife and gently scraped it, sandpaper has been suggested elsewhere, once done scrapping, wipe down to clean any residue. The top cones are only part accessible, after cleaning mine the noise still persisted but acceptably lower than before. I think if you completely take apart the unit you can clean this cones better.
8. Reassembly is the same is opposite of disassembling.

Hopes this helps you.

pull the filter and cells out. close up and see if the noise is still there. If it is then you have an istallation problem. if not start putting parts back until sound returns.

after cleaning is it dry. you might want to take apart and see what is clicking wheel or some thing hard to tell since i can't see it. as far as options . check with the manufacture google it check them out on line hope this helps. Tom

Its just a wear in the ozone plastic its normal after continued use

Sounds like Motor or bearing is failing.
You could order parts but you will find it less expensive to replace unit. Than trying to repair.

Please rate. Hope this helped. If i can help you further let me know. Good luck!

just take it to ur local dealer they will replace it or fix it.