how can i find out if it is the fan or the speed control switch?

i have a renault laguna w reg 2000, the fan worked okay on setting 1, then that would not work,so i put it on setting 2 that worked for a while then that packed in, then i put it on setting 3 then that packed in,
What i would like to know is, is the fan on its way out,or is the
speed control switch faulty