Heat triggers the problem by making the plastic brittle. But, the root problem is lack of support. That wide area between the cluster hump and passenger airbag doesn't have enough support ribs to keep the plastic from flexing. The left and right ~25% of the dash doesn't have enough area to flex so the cracks form where the flexing part meets the non-flexing part: On the left side of the gauge cluster and on the left front corner of the passenger airbag. Sure, more cracks develop elsewhere but these are pretty much guaranteed. I think the dash has been revised to include more ribs/webbing for the center area. It may or may not have a new part number.