1996 Nissan Maxima blower only turns on on #4

hi, my 96 nissan making cool's fine,but the a/c blower only runs on #4 speed which is full blast.on #'rs 1,2, &3, the compressor come's on but the blower dont do any thing unless you turn the control to # 4.i have already changed the a/c control's on the dash board but nothing same to change...any idea's, please help.....thank you