98 sentra - fan problem

the a/c-heater fan on my '98 sentra only works on setting 4. on setting 1 thru' 3, the fan doesn't even blow. on 4, it blows full force. I assume it is the switch? anyone know how to access this switch or has had similar problems? thanks

There is a resistor plate that reduces fan speed at 1 through 3 settings. Search for a flat connector (5 or 6 wires - 5cm (2") long) attached to the resistor plate (it must be at the fan housing - right underneath). Detach connector, unscrew the plate and take some resistance measurements. Maybe you'll find the problem even visually. I've corrected the same problem couple times repairing (soldering) the lines on resistor plate. A new one might work as well!