Rick, the actual switch part under the dash has a bit of a tooth that fits in a little notch to keep it from turning while you unscrew the face bezel all the way off - in other words, hold the back, turn the front!
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics