I have a true True Air Model 04381 by Hamilton Beach. I need a filter replacement. It says it uses a 3M filtrate filter but nobody carries it. Can you help me locate one. They said this model is discontinued.

Resetting Filter Life:
After replacing your True HEPA Filter, place the Pre-Filter
back in and close the Front Panel. While the unit is on, hold
the Filter Reset Button for at least 5 seconds until you hear
the beep. After the beep, the Filter Replacement Indicator
will disappear. Your Winix True HEPA is now reset

you can call (877) 699-4649 for more help

The Replacement Filter 4 1/4 x 10 1/4 cost around $25. You can purchase it at these websites: http://www.databazaar.com/Office-Equipment-Equipment-Supplies/Office-Environment/Air-Cleaners-Filters/3m-MMMOAC50RF.html and http://www.clicksupplies.com/storefront/Filtrete-Replacement-Filter-4-14-x-10-14-P-29564

check at amazon.com

Go to link below to see how to remove the filter.

http://www.brookstone.com/pure-ion-advanced-cleaner.html?his=2%7E46337%7E2%7Eroot_category%40kwd%7E561274p&searchRedirect=true

These units usually put out ozone into the air in your home which is a known lung irritant. Sometimes they will call it an ionizer or something like that. If you truly have indoor air quality issues the only way to properly attack it is through three steps
source control - what's causing it(uv lights to kill it usually)
ventilation - bring in fresh outdoor air and exhaust stale indoor air(ERVs and HRVs depending on your climate some dealers won't sell these if they don't offer it to you they are dumb find someone who does they are Recovery Ventilators)
filtration - a whole home filtration system (look to dealers who carry Lennox who is the only company with a 100% ozone free product line and the highest filtration rates available on the market "MERV 16" filters or Trane is ok as well as Carrier systems)
You can look up the Lennox Merv 16 filter it was rated #1 in Consumer Reports december 2007 as the best whole home air filter above the trane clean effects and others. can be bought and installed for around 400 bucks to 1000 dependeing on how hard it is and ask about the pure air system if you want higher levels.

You can by the filters at target and the replacement filter should come with instructions on how to change it

Is it possible you put the filter in backwards?

http://13520-replacement-charcoal-pre-filters.com/honeywell-enviracaire-hepa-air-cleaner/

I'm not exactly sure what is the problem with your unit since in the title you say it won't start, but in the body you say it won't stop!

If it won't stop just unplug it. I'm assuming that's not your problem though.

If it won't start check the 2 safety interlocks. These automatically stop the unit when you take off either the front cover or the top cover. (This is so you don't stick your fingers in the fan while it is running and sue Hamilton Beach.)

On my unit the top one stopped working because the small plastic tab on the bottom side of the top cover broke off. This tab is designed to press into a switch inside the unit when the cover is properly installed. I over rode the switch by placing a small folded up piece of cardboard into the switch slot and taping it in place. This activates the switch full time. The only drawback is the unit will not shut off automatically when the top cover is removed. This could be a problem if you have an inquisitive toddler or child around the house. I only recommend this modification if you don't have small children around!

The front cover has a similar interlock and can be disabled in much the same way.

I hope this helps.

Here is the link; http://www.hamiltonbeach.com/cgi-bin/main/co_disp/displ/pgname/trueair_home/strfnbr/20 Hope this helps :)