I have put four heater cores in the truck in 5 years. Ford paid for one because it was less than 6 months since the last one went out. Yay.

a/c on left side, heat on right when a/c is on. I still don't have this fixed. It took 3 weeks and 2 dealerships to figure it out. I go to get it fixed and the part needed was discontinued by Ford. Still remains unfixed.