First thing, check the fuse then the switch. If those are good, then get out your trusty multi-meter and check for voltage at the motor. If no voltage, then you have a problem upstream of the motor. If you have voltage at the motor and it still won't run then obviously the motor is shot. I have never replaced a blower motor on an '87, but I can imagine it will be an all day affair, especially if you have air conditioning.