As I mentioned in the previous post, I broke my elbow while hiking, recently, and so haven't been able to take the train as often as I used to. Nonetheless, I did run into a few hot cars.
On 8/29/2008, the Stoughton #917 train had a hot car: coach 507
On 9/3/2008, the Franklin #715 train had a double coach without working AC (the first I've ever seen in which the AC was disabled throughout): coach 716. It was horribly hot. I didn't have a thermometer, but I feel quite safe in saying that the temperature was approaching 100°. The coach had the usual effect, too; people jammed into the adjoining coaches, crowding them dangerously. Since the Franklin #715 coach has been getting more and more crowded lately (and they've been shorting us a coach fairly often, too) this was a real problem.