Diagnosis
Dust buildup on the intake and exhaust grills reduces efficiency and can cause a burning smell. You need to clean it without damaging the fragile ceramic element inside.
How to Fix It
Unplug and let it cool completely. Use the brush attachment on a vacuum cleaner to gently suck dust from the front grill and rear intake slots. For stubborn dust, a can of compressed air (held upright) blown *across* the grills from a few inches away can help dislodge it.
If That Didn't Work
Never use liquids, sprays, or insert anything into the grills. The ceramic plates are brittle. If dust is caked on internally from heavy use, it's not designed to be opened for cleaning.
Heads Up
A slight 'new' or dusty smell for the first few minutes of a season is normal. A persistent acrid or electrical burning smell means stop use immediately—it could be dust on hot electrical components.