Why does my Breeze randomly change fan speeds and purification levels?

The most common reason for surging or changing power levels is a loose connection somewhere.

1) Make sure the plug in the back is inserted firmly and the wall socket is live. The wall socket should not be powering a high-use appliance such as a furnace or refrigerator.
2) Check to make sure the back screen is inserted firmly, depressing the interior safety switch. (It will click when positioned correctly).
3) Make sure the plate is inserted firmly and correctly in the top and bottom "tracks" inside the machine. The metal contact fingers should be pressing firmly and evenly on both sides of the plate, in the metal screen area. You can bend them a little to increase the pressure. You may need to adjust the upright white ceramic posts to align the contact points. (Sometimes they twist.) Make sure the screws that hold the contact points are in firmly.

If none of these troubleshooting suggestions solves the problem, it may be malfunctioning because of computer issues. Unfortunately, Vollara (new name for EcoQuest) no longer services nor sells the Breeze model. However, customer service will inform you of your options. 800-989-2299.
You may also attempt to locate dealers who still have the Breeze in stock, and/or parts. You would need to do this by first asking Customer Service to locate a dealer in your area. They'll give the dealer your number, hopefully the dealer will call, and you can ask them to inquire among their associates.