If a pump's control switch is set to auto but the pump is not turning, what might be the issue?

When a pump's control switch is set to auto but the pump fails to operate, one plausible issue is that the fuse is blown. A blown fuse interrupts the electrical circuit needed for the pump to receive power, preventing it from starting even though the control switch is in the proper setting for automatic operation. This is a common cause of failure in electrical systems, as fuses are designed to protect the circuit from overloads or faults, and when they blow, they disable the device to prevent damage.

In contrast, if the pump is primed, it indicates that the pump is filled with liquid and should be able to operate properly, meaning this is unlikely to be the issue. An overheated motor can cause problems as well, but this typically results in the pump shutting down after running; it would not directly prevent starting unless there is a thermal overload protection in place that has tripped, which is not guaranteed. A clogged filter may restrict flow and lead to operational problems once the pump is running, but it would not prevent the pump from starting when the control is set to auto. Thus, the state of the fuse is more directly related to the immediate inability of the pump to turn on.