Fan only runs in high position.

[dogfox]

I must set the fan in the highest speed position for it to run. All funtions @ that speed seem fine. Any thoughts of what the problem could be?

[Spike1]

There are usually 2 resistors that are used to decrease the power to the fan motor for low and medium speed. I'm not sure where Nissian hids them. They are usually stuck in the side of the heater box on most cars. I would replace them and if it happens again it's a sure indication that your blower motor is getting sick.