Starting around 18 months ago my 2012 Prius (just under 80k miles) started running the traction battery cooling fan a lot more than it used to (I bought this car new). Even some days when it's cool (50 degrees F outside) and I am driving very sedately it'll be madly whirring away, only slowing down when I come to a complete stop. When new(er) it ran on hot days or when getting a heavy drain (up a steep hill) or a heavy charge (down same), but not on cool days and level roads like it does now. I don't carry any pets in the car. 90% it's mostly just me and my briefcase (it's my work commuter car), though occasionally my wife and kids will be with me. Despite this do you think it's worth looking into cleaning the fan and duct? Any other thoughts what could cause this?
OK. Do you frequently drive with the windows down? If not, I'm not sure how your fan would be clogged enough to warrant running a lot. Check the vent for any obstructions (paper) if you haven't already. I would also suggest getting a monitoring app to see if the battery temps are really causing this. It's a little early for weak/failure but.... Where do you live?
That I do. I have the solar roof and have it (and the windows) open a LOT - at least in the warmer months. I live in NE Ohio so actually it's only about 3 or 4 months out of the year where the weather isn't miserably rainy or cold, but anytime it's above 65 and no rain (and I'm not on the highway) I have everything open. I am not much for a climate-controlled life. What kind of monitoring app is there for this?
ScanGuage, with an extra XGauge, is what I've used. There's a number of phone apps too? Still, I would just check the fan first, it takes an hour or two. You can watch @NutzAboutBolts video here (#21): Nutz About Bolts Prius Maintenance Videos | PriusChat I wouldn't bother to remove the rear seat: it's just access a single bolt, below the fan intake grill, and you can just push the seat and back pillows apart and reach it. Also, I just got to the fan, then cleaned it without full removal.
The fan doesn't look that far back. I wonder if I couldn't remove the grill cover and at least see back there (if it's dirty or not) before pulling everything apart.
Not really, you have to pull the parts off. Hatch floor is stubborn, I left most of it's fasteners off when reinstalling, to make next time easier.