Get the heat out
How do you get the heat out of your enclosure and away from critical components? There are three basic enclosure cooling methods:

• Natural Convection Cooling
  If the ambient temperature outside the enclosure is cooler than the inside of the enclosure, then the heat can be dissipated into the atmosphere by radiating it through the surface of the enclosure and through the use of louvers or exhaust grilles with filters.
  
  
• Forced Convection Cooling
  If you have clean and cool ambient air outside of the enclosure, then a simple forced-air system may be adequate. A system such as a filter fan and the associated exhaust grille with the appropriate filter may be an acceptable option.
  
  
• Closed Loop Cooling
  A system that will keep the ambient air separate from the internal enclosure air is needed if the environment is harsh, if there are washdown requirements, heavy dust and debris, or the presence of airborne chemicals, and the ambient temperature is as high as or higher than the desired internal enclosure temperature. Enclosure A/C units are an example of a closed loop air conditioner system.