Tonight for the first time I heard a fan sound coming from the back seat after driving in traffic for 45 minutes. It was coming from the vent in the back seat. I didn't know that that vent had an electric fan, or does it? I assume it was the battery being cooled? I have never heard this sound before. Does anyone know when the fan comes on if it is indeed a fan?
I think if you take out the under floor tray in the hatch area you can see the fan housing. There's some pics at lucsious garage regarding dust accumulations in 2nd gen fan: Luscious Garage | Blog | Prius battery cooling fan cleaning, P0A82 I'm not sure if things are different with 3rd gen. I put a piece of fairly open mesh vacuum motor filter behind that back seat grill on ours. I've never heard ours cycle, fwiw. Then again, I'm not the principal driver.
https://picasaweb.google.com/105684...nFrancisco2009?authkey=Gv1sRgCILH8tvp-8_pjQE# has some pictures of the 2nd and 3rd gen packs and shows the the 3rd gen's fan. I took these at Prius Connection San Francisco in March 09.
Owners manual page-33 Hybrid battery air vent "There is an air intake vent on the side of the rear right seatback for the purpose of cooling the hybrid battery (traction battery). If the vent becomes blocked, the hybrid battery may overheat, leading to a reduction in hybrid battery output." Ken@Japan
Pretty much answered, it's the battery cooling fan. I find it to be more noticeable in the Gen III compared to my Gen II, but more often than not my radio blocks it out and I never hear it.
