I don't think you are missing anything. If the controls are in any position other than "off", the fan should operate. If you have a home warranty with your new house, I would make a claim ASAP. Otherwise if you have basic electrical tools and skills, you could try to troubleshoot the unit. Chances are it's either the controller, how it's wired, or the fan. You might also want to take a look at the ducts and outside air intake / exhaust to look for leaks and blockage.
Here is a link to the owner's manual: