What makes heater fan stop working then start when bumped then stop again?

A heater fan that stops working and then starts again when bumped likely has a loose or faulty electrical connection, such as a worn-out wire or a failing motor. Bumping the unit may temporarily restore contact, allowing it to run again. Additionally, debris or dust buildup can impede the fan's operation, and physical movement might dislodge the obstruction. Ultimately, it may require cleaning, tightening connections, or replacing components to ensure consistent operation.