Ok, here's an update. I have the base model, the cheapest of the cheapest. This means no AC.
What the dealer told me, it's by design. When starting from cold in the morning, and blowing the air right away, the air intake near the dash, sucks the air, blows by the heater core, that is still cold, and can reach the vents easily. Because I don't have the A/C, the evaporator coil does not break it down either.
So came the questions of the "pollen" cabin air filter. They dodged that one. It doesn't exist I'm told! LOL....
So, in the end, I was told to turn off the fan before starting the car, set the air source to recycling to close the trap, and only turn it on when the car has warmed up.
Not quite was I expected.
I will open that well and use a glue gun to add a fine mesh behind. I will test prior, but I'm thinking mosquito screen.
This, along with a darn cabin air filter and I should be good.
Neo: yeah, cool/hot air works fine. Definitely noticeable in winter when the engine is warm. After 30min, I can't leave the heat full speed, it burn my feet. Takes a while to heat up, but once it's warm, it keeps the car tropical warm.
View my fuel log 2015 Micra S manual: 7.7 L/100 km ... 36.6 mpg (Imp) ... 13.0 km/L ... 30.5 mpg (US) ...