2000 Nissan Quest Heater switch only works with level 4

No, that will most likely be a bad blower motor resister. It's located in the blower housing, right next to the blower motor.

I have one more question, a friend of mine have a nissan maxima 1998. Have same problem but only level 3 work. So relace the blower motor resistor will fix it ? Thanks

Yes, most likely. In rare cases it can be the switch but 9 out of 10 times it's the resister.

Thank you very much. I fixed my Nissan Quest.

Glad to hear that. Feedback would be appreciated