Steve,

It does happen more when the temps outside get above 90, but it has also happened when the temps weren't even above 80 a couple times. If what you say is true, that could be part of our problem. We never have the vent covered though.

Another thing that confuses me is that we had the car all through last summer and the temps got just as high and this never happend once.

I really think we are a candidate for the replacement 12V, but the dealer said we don't have any service bulletins that apply to our VIN. I think he looked up recalls though.

I am going to take a printout of this thread as well as a printout of the service bulletin next time I take it in. It started doing this with 11,000 miles on it, and there's no reason for one of the 12V batteries to be bad yet unless it was just a dud in the first place.

Correct me if I'm wrong on this, but the two 12V batteries aren't the NiMH hybrid battery, but more like normal car batteries (even if they aren't quite normal car batteries).

Thanks for the response. I think my conclusion so far is that our 12V in the back is a dud and therefore the heat is really getting to it this summer more than normal. It's really unfortunate as this past month I have enjoyed driving the car like I used to.