Why might a motor not start if dirt is suspected on the centrifugal switch?

If dirt is suspected on the centrifugal switch, it compromises the functionality of the switch, which is critical for the motor's operation. The centrifugal switch is designed to engage and disengage the motor’s start winding based on the motor's speed. When the motor reaches a certain speed, the switch opens, removing the start winding from the circuit. If dirt accumulates on the switch, it can hinder the mechanical movement necessary for the switch to properly open or close. This interference can prevent the start winding from disengaging, leading to the motor not starting or running inefficiently. Maintaining cleanliness is vital to ensuring that all components, especially mechanical ones like the centrifugal switch, operate smoothly.

Thus, the presence of dirt can indeed obstruct the proper contact required for the switch's operation, directly affecting the motor's ability to start.