If you have a problem with your PMA overheating it may be a slipping belt causing the problem. On high amp output, the PMA or alternator is under a large load and starts to overheat when the belt begins to slip. That's why high amp PMAs or alternators use dual belts.
This fan and pulley is used on our PMAs when using a gas motor or hydro, a must for keeping your PMA cool! Allowing your PMA to overheat will cause it to burn out. A fan and pulley are not necessary when the PMA is being used for a wind turbine.