Once the low amp circuit is complete the relay will close, connecting the 30 pin which is 12V power from the battery, to the 87 pin which allows this current to go to the fan, window motor, fog light, etc. which will have a wire connected to ground. When this circuit is complete, the component will operate or turn on.

When the "switch" is turned off, the engine temp or AC pressure lowers, the switch will open which in turn will cause the 87 and 30 pins in the relay to disconnect and the component will turn off.