Today was cold so i turned on my heater and it dont work unless the fan speed is all the way up to 4 if its not it dont work does any body know why?

 

it might be the fan switch itself (the **** you turn) since 4 is typically the least commonly used setting it's the last one to go out, you'd have to pull it out to test it

 

most likely if fan does not work on 1-2-3 speeds you got a bad blower resistor

 

how would i check the fan switch or if thats not it how do i check blower resistor

 

if you look at the blower motor under the dash on the passenger side you'll see a few wires going to it, trace those wires back and they should go to a little box and that's the resistor... Hopefully that still works on the 02 models...