you need to find a way to vent out the hot air and bring in fresh air, is there a way you can put a vent fan in the top of your grow space, to pul out the heated air?

it sounds like a good set up, but you need more ventilation, and you might want to put the light a bit higher from your plants.
ok here is a little test which i do to see if my light is too close, place your hand, palm down, at the top of your plant, if you can hold your hand like that between the top of your plant and the light with out your hand getting too hot, it`s far enough away, but if your hand gets too hot real quick, the light is too close. test it , raising or lowering using this method should keep you from burning your plants