I have the same problem with my 2014 Transit Connect. I get no rear heat and cold air comes through the upper rear vents even with the control turned to heat. I took it to the dealer in December and they said my rear electric heating element wasn't working and that none were currently available from Ford. The dealer said that it was unusual for a part to not be available and that a redesign might be happening. I heard back from them a couple weeks ago and they still have no answer from Ford.