Ecoquest Purifier was working when I went to work. When I returned, it was not running and would not start

It doesn't sound fixable in the field. It may be a control panel issue. Contact Vollara (which bought Ecoquest) & get through to tech support. 800-989-2299.

I've read from some other posts on here that Ecoquest is good about returning the items and replacing them.

It will operate without a purification plate, as long as you are running in RCI mode or normal mode. If you normally run the purifier with some ozone output, then you will need a purification plate. Hope this helps you.

By all means run the unit while you wait for the new RCI cell. The purifier will be less effective in killing germs while the RCI cell is out. It will still work to reduce the allergens in the air. Hope this helps you.

The FA2 uses several technologies for purification. The "normal" mode produces purifiers using the honeycomb RCI cell and UV light. This has little or no odor.
Open the back of the machine, or shine a flashlight through the front to make sure the white 4" plate is inserted, closest to the back screen. If it isn't, you'll need to either put one in, or order one from Vollara (new EcoQuest company name) @ 1-800-989-2299. You can use #16618 as the dealer referral number if you are no longer in touch with the registered distributor who sold you the machine.
When you turn the machine to "purifier," you should then detect the "fresh air" smell. You'll see square footage numbers, which you should set according to the immediate area, NOT total for the building! Also, the machine directs the air flow to the sides in a "V" shape, rather than straight ahead. So if you're standing close to the machine, smack-dab in the front/center, you may not be able to smell any of the purifier!
When the machine is on "Away" mode, the purifier and fan are ramped up to maximum strength, and you can choose 2, 4, 6, or 8 hours for this super-sanitization. At then end of that time, the machine will return to whatever setting you had it on for daily operation. No people or pets should be in the immediate area, because the purifier is strong and likely to be uncomfortable. (Set the timer for 2 or 4 hours less than the time you expect to be "away," to allow the purifier levels in the home to return to a pleasant level.)
Hope this helped.

fuse is in back by power plug, but this unit sucks!!! i went thru 5 of them, the power supply keeps failing. they will rework it under warranty but it takes forever. call salesperson. good luck. I gave up on them and went to oreck. it sucks too, just plain unhappy cause the ecoquest ROCKS when working correctly, but the oreck barely does job

Call toll free 1-877-710-0057 between 8: 00 AM and 5:00 PM Eastern time and they will gladly help you.

Go to http://www.ecoquestintl.com/dlrdown/website_om/BreezeOM_ENG.pdf that should do it :)

My husband came home and checked out the unit. He discovered that the cord was bad, so he replaced it with one we had. It works fine. The cord plugs into the unit at one end and into the wall at the other end. There was no rewiring needed. Problem solved!

Its probably the starter. Manual says to replace both lamp and starter at same time.