you need more VENTILLATION not CIRCULATION! a fan blowing air around the space is circulation and does very little to lower temps. ventillation is exhausting the hot air from the space and bringing in cool air to replace it.

what you said about letting to much light out is strange. if you leave the door open the light does not escape and not get to the plants. the problem is that if there is a light leak it can compromise the security of the grow and also if light gets out that means it also gets in and if your dark cycle isn't completely dark then your plants will have huge problems when you try to flower them. just something to think about. good luck