2016 Prius 2 fan in backseat.

It is important to ensure that the vent isn't covered - with a seat cover, blanket, stuff on the floor etc. I checked mine recently - it was as clean as a whistle - at 25,000kms. I never drive with windows open, and in recirculate mode. But - if say you have a hairy dog in the back seat often, or drove often with windows open, maybe it could get clogged quicker.

And there is an additional vent not shown - it is assumed it is to exhaust from the battery ventilation?:

 

welcome!
yes, the filter/grille needs attention, and the fan should be cleaned periodically, if you carry shedding animals or the like.

 

Pop the rear seat off I think. I would wait a while yet, unless you're really curious.

 

If the filter is clean then the fan should be.

 

The battery cooling air vents to outside. Cleaning the fan is not a trivial matter, requiring disassembly of a bunch of stuff. Some here have done it on the 3rd gen and posted "instructions". Most who have done it find it pretty clean.

A note for "newbies" - the battery "cooling" relies on you having the interiour of the car cooled by the A/C system.

 

It takes an hour or two, not that hard, on 3rd gen. It helps to have compressed air of some sort.

 

I was led to believe that the Gen 4 is a completely different arrangement to the Gen 3 - because the battery is moved to under the seat.

Behind the screen is a filter, which in my case was like new - I'd only look further if the filter had been clogged.

If it vents to outside, do you have any idea what the centre floor grille is for?

[Gen 3 - there is a YouTube on cleaning the fan

].

 

At the Las Vegas 4th gen reveal the intrepid PriusChat team managed to yoink the rear seat bottom up and off, took a matter of seconds. The took some pics which should be around here, there's a collection in the gallery.

 

should be in the service manual for 15 bucks.

 

There's some better pics, I believe they're around here, in this folder somewhere, views from the passenger side door.

Media for user: Danny | PriusChat

 

The Manual just recommends vacuuming the grille. The grille can be removed and there is some sort of filter behind it. I guess it could be gently vacuumed too, if needed.

@Elektroingenieur may have some hints for those wishing to dive in further.

 

Off topic but: contrary to the 3rd gen video posted up the page: it's not necessary to remove the rear seat bottom. There's a single 12 mm (socket size) bolt that needs to be removed, to free up the section of seat back with the intake grill. It's in behind the seat, but accessible through the divide between seat and back, with an extension.

I suspect the 4th gen repair manual will say nothing on proceedure for accessing the fan for cleaning. I've never found anything in 3rd gen manual, and it's not really necessary, you can just follow your nose.