ice box vs exhaust for grow tent??

im using a 4x8x7 grow tent with 2k 1000watt 8inch aircool reflectors with a 8inch active air inline fan, the tent is in garage where the temps are 40degrees im pulling air threw a straight line threw the lights, im using the cold temps in garage to keep tent cool dont really have to worry bout exhausting air in room since it is so cold and garage is not insulated,its bout 70 degrees in tent.... would it be better to use the ice box?? especially when summer arrives and garage temp rises... what would be the best route to keep tent temps in check i really dont have to close doors much in tent either so that helps with heat build up..

Is your ice box in your garage? Any possible of getting a window-mounted a/c unit in the garage somewhere?