As far as I know, I think it was included on the first batch of scholarship 1997/98 cars that were ordered with a heater, and then when the heater was removed for racing, it overheated (Caterham only had one test car, and that had a heater, so didn't show up the problem!). It was then omitted from all later cars.
I took mine out in early '98, but the new owner has it now.