I have had this problem since the end of winter the blower motor works fine on 1 2 3 with both the heater and ac, but when i select 4 it just stops. Nothing at all like its off switch back to 3 2 or 1 and it works fine any ideas where to start

 

This is most likely the blower motor relay that has failed, but check your fuses as well. The resistor block controls all but high speed.

 

where is the relay ? i checked my fuses and i only have 1 2 3 no high any part number or anything i can look up thanks

 

nevermind i got it, The pigtails that a gray in color that connect together under the hood, Had a bad connection problem solved