The Primes Battery is fed by TWO blowers, from the vents to the left and right of the rear passenger compartment and a least partially exhausted by a central vent directed to the (and out of?) the bottom of the car. Too much trim to remove to follow it further. I just installed temp sensors on the ducted part and the un-ducted part. Keep the filters next to the rear passengers clean. (Routine maint by Toyauto should take car of that. Perhaps check more often if you ride with pets in the back.
it is a 5 year old thread, sadly many of the respondents are no longer active PriusChatters. Others (like me) will no longer have a Gen 2. It is a Gen 2 thread, while time marches on, there are new forums for those new Generations. Starting a new thread in the prime forums will get you more knowledgeable Prime owners than posting in a Gen 2 forum.