2002 ford taurus...heat problems..please help thank you!?

2002 ford taurus... heat will work on lowest setting, and when im going over 70 mph it blows out more heat, my boyfriend changed the thermostat and fuse none helped i was told it might be a switch or a blend door?? How much would it cost with labor to fix this? Thanks alot!2002 ford taurus...heat problems..please help thank you!?It sounds like a resistor problem. For each speed selection on the fan the power goes through the resistor and lowers it to say 3 volts for low speed and 6 volts for medium. After time the resistor breaks down from the heat it generates. It is most likely located in the air duct right after the blower. And will probably have about six wires going to it.

What comes in a duvet set

how long does it take to learn asp