I've found that a buildup of minerals is in the bottom of the reservoir and you need to open it up, pull and rinse the filter, then the bottom unit out and scrub good. Then gently clear the debris off of the heater unit as best as possible. Then reassemble and let dry a bit. The Reset goes off on mine only when on HI, but never on low. I am now trying to clear off the crud from the heater to see if this resolves it but in the meantime, you can or should be able to use the LOW at least.