We have a 97 mark 8 the a/c works great but when we switch to heat the a/c stays on , no heat. The vehicle doesn't over heat, the car runs great and has been well maintained. The vehicle had 8,000 miles on it when I got it so I know its history. We live in So. Florida so we don't use the heat very much, but there are days that we do need it. Any information will be helpfull.