dryer wont stop when clothes are dry

I have a Maytag dryer, model # LDG7500AAL that come with the house I just bought. When I set the dial on the more dry, less dry it will just keep running until I stop it manually. I have tried it as close to less dry as possible but it still keeps running. I have checked the wires on the back and everything seems to be hooked up. Is there a sensor somewhere that I need to check or replace? Any help would be appreciated.