You need a scanner that will read the srs system. A cheap code reader does not do that. Find one on eBay or amazon that will access the srs, abs and transmission modules so you can properly diagnose your issues. You will have an srs code of some kind. Has you vehicle been in an accident? Someone hit a deer or other more serious incident? You will have to spend between $100-200, read the reviews make sure it works with a Nissan or is guaranteed to work with a Nissan.
You probably have a short in the wiring to the blower.