Diagnosis
The machine is hitting its internal over-temperature safety cut-out. This is almost always caused by a clogged intake filter.
How to Fix It
1. Power off and unplug the machine.
2. Remove the HEPA/carbon composite filter.
3. Tap it firmly, filter side down, into a trash bin to dislodge thick dust.
4. Vacuum the exterior of the filter with a soft brush attachment. Do not wash or rinse it.
5. Reinstall the filter, ensuring it clicks fully into place.
If That Didn't Work
Check for objects blocking the exhaust grilles at the top of the machine's loop. Even a magazine or curtain too close can cause recirculation and overheating.
Heads Up
The HP07 has a 9-hour automatic shut-off timer for safety. It will turn off after 9 hours of continuous heating, regardless of the thermostat setting.