Ford Repair: air control, mode selector switch, ford taurus

Question
my blower wont run and the radiator fan wont kick on when I turn on th AC but it will operate normally.(I was told the fan should run constantlyu when the ac ac on)There is no noise of any type but the vacum operated doors when i turn the control switch for the heater,AC.This is on a 1990 ford taurus

Answer
Hello Randy,
    The mode selector switch sounds like the most likely cause, the electrical part being faulty, but not the vacuum part. It can keep the blower from working also. If you have more than one problem like that, then you have to look for a common cause, like a power feed (fuse), or bad switch, or bad ground.