Proper Air Flow Evaporative cooler ?

Okay so i live in a dry climate and have a mastercool and the pads are new and so is the pump. Today its 100 Degrees and the humidity is at 6% , so shouldnt my temp inside the house be around the mid 70s?? I went up on the roof to ensure everything was working as it should and the pads are cold and everything seems in order. I have my windows cracked about half and inch trying to get proper circulation. Any ideas ?? oh and the temp inside my house right now is at 87 Degrees... Any help will be appreciated, thanks !