It would depend on the year, make and model of Buick. You would need to supply that information for us to have any chance of usefully answering the question. Sorry.
The blower switch is the knob you turn on the heater control in the dashboard. If you are talking about the blower motor resistor, it is located in the passenger's foot well area, mounted in the heater box.
The problem is most likely a faulty blower control module.
you will find it in the heater box, also where the blower is. it is easy to remove.
where is the switch resistor on 2003 buick
Blown fuse. Burned out blower speed resistor. Faulty blower switch. Bad blower motor.
Check the fuse
dealer or junkyard
Check the blower resister
If a 2000 Grand Am sometimes has the heater blower working and sometimes it won't, the problem could be with the heater relay switch. The heater relay switch lets the heater blower know when to come on and when to go off. In most vehicles this switch is behind the glove compartment. This part sometimes gets corroded from condensation in this area.
The heater core is mounted to the passenger side firewall on the 1988 Buick Electra 307. The blower motor needs to be removed to access the heater core.
Check to see if you are getting power and ground to the blower motor - if so blower motor is bad. If no power possibly fan switch or selector switch Also check the blower motor resistor, found in heater plenum.
in the middle