my air only would work on high today, I can't get it to come on.

Hello, something related to your blower motor is not working properly. If you have an automatic temperature control feature on your Nissan, you'll have to have a diagnostic test performed on this component to see what is happening. If you do not, you could have a problem with the blower motor resistor, not conveying the proper power to the blower to turn on so you have air flow. In either case, if power is at the blower motor (which you can test with appropriate test equipment), and the blower does not turn on, then the motor itself could have failed. I lean towards resistor or blower controller as the cause of failure, but only a hands on diagnosis will tell you.