How do you install a blower motor relay in a buick regal 2001 ?

my buick regal's a/c and heating will only work on high when you first start the car. then when you turn in down or off it wont work at all. whats wrong with it?|||It sounds like the resistor for the blower..not the relay. Relays very rarely go out. The resistor is behind the blower motor/fan...usually behind the glove compartment.