So as per OPs comments I've been looking into this on my Zed too. Same symptoms. Fans off until circa 100 degrees, then driver's kicks in, passenger does nothing. With AC on, driver's spins, not passenger's.
Whilst I was in garage today for unrelated issue, tech plugged in computer and set fans to low. Driver kicks in only. He then set to high and passenger fires up too! No problem, no struggle, just on.
I put this down to dirty fan contacts on passenger side at first, but no amount of banging or finger wiggling makes passenger fan spin up with AC on. However, it breezes into life with the computer telling it to go high.
So I'm thinking, stage one (low) is driver side and stage two (high) is passenger side as well, I know this contradicts the workshop manual, but is there a slim chance Nissan got it wrong in the book or it's some sort of regional variant?