Grow box heat problem

So I'm having a huge heat problem. The plants cool with a fan but hella dry out the soil what should I do? And how can I keep the humidity up?

You are going to have to be a little more descriptive. Any pictures? A forum can solve your dilemma but we need more info, Space? Lights? What kind of fans?

water more? seriously you were pretty vague here. You said heat problem, but you didn't tell us what your temps are.

Oh this will be fun. I am gonna guess, solely based on information obtained through months of research that he does not have adequate ventilation and his grow box or enviroment is to small. A large area would not create a serious amount of heat unless it was in a 90 degree room to begin with. Most houses run 70-75 on average. If he has a tent with a high powered lamp which I doubt he does with growbox in the title, then were talking a whole other scenario. I'm going with not enough ventilation of air let alone fresh air and grow box to small

The box is about 2x2x4 with a 150watt hps at the top with a hole cut at the top. And a fan at the bottom blowing air into the box
With the fan on temps stay around mid 70s to low 80s but the soil dries out. Without the fan fan temps are around. Mid 80s to mid 90s
Ill get pics when I can

water them more, or a humidity dome?