Recently I got my roof replaced. The contractor installed ridge vent at top. Before that I had gable vent on one side and an attic fan on the other side of gable vent (my central a/c-heating unit is in the attic). The contractor repeatedly said no need to cover the gable vents but just unplug the attic fan and not to run it. He says the gable vent infact helps air culation. Reading on line suggestions everyone says I should close the gable vent to avoid short-circuit. Any suggestions?