I am not an expert but I am just telling you what I did to get mine to work. I cleaned it several times and I even took a shop vac and used the blower side and tried to get as much dust out of it as possible. Then I put it back together and I put another air purifier behind it(that I bought after my gp broke)that blows are through it and I left it like that for a couple of days and now it works fine. Maybe you are having a different problem than me.

Oh there are a lot of known issues! I used to work for sharper image and I believed in this items very much so until mine broke. However after a year I figured out how to fix it. Take the big square collection grid out and the back screen off. Now get you a thick rag and be very careful because there are several tiny wires going up and down. Smaller than dental floss, you need to be very careful because you can either brake them or slice your finger wide open( Under any circumstances I can not be held liable for the information I am giving you try this at your own risk). Now with the towel very gently go up and down each wire like you are polishing a brass pole(once again these wires are thin and can break or cut you). Do this from the back side of the unit and from the inside where the collection grid that you took out sits. Take your time and be thorough, and presto your 400 dollar air cleaner is working again.