Since laptop users are mobile, they're frequently using different printers. When sending a document to print sometimes my MacBook selects the wrong printer, when it doesn't print I select a new printer and print again. But I forgot to delete the print job sent to the first printer, so my Mac keeps looking to print at the other printer causing the processor to heat up and the fan runs constantly.
Therefore, open System preferences go to Print & Fax, then select the printer that has a document in the queue, delete the print job and the fans shuts off within a minute -- and stays off.
The laptop will stay quiet and cool, the battery will last the usual amount of time, and MacBook mobile life is good again.

