Hi Sp0nser, your thread got derailed a bit but don't worry. The issue is that when you close up your greenhouse, you are concentrating the heat. When you put a fan in that now-hot room, you are just blowing heat around. If you want to have the greenhouse setup in the house, the easiest thing to do is to allow some ventilation in.
YES this will lower humidity, but you're stuck right now because you don't have a way to cool the air besides letting cool air come in.
You can open the greenhouse door and use plastic sheeting over the shelves, to trap some humidity near the plants, or otherwise bag the plants. It's not going to look magical, but it's better than cooking your plants
You may find that you can strike a balance with opening and closing the door as needed to cool it.