yes, first of all plz ensure that ; 1- fans belts are tightened ,its important for the reason that afan with loose belt will exhaust 15--20% less air 2- fans shutters are fully opened; slanty position of shutters is not desirable 3- fans blades must b free of dust all the time , especially during hot weathers, bcs a dusted blade fan efficiency is reduced to 20-25%. if after committi ...