hey my fans (inside) dont work right they go to level one thats all what part do i need to replace
check your cabling but my bet would be the fan control box / heat and vents next to your cd player but first might be worth just checking the contacts on the board when you pull it out if its dirty
will be the fan speed resistor in the blower fan, behind the glove box, little orange thing screwed into the fan housing with 3 or 4 wires going into it.
most likely the fan speed slider control contacts and/or the electrical connectors on it.
Often when people fit stereos, they accidently knock one or more connectors off.
I had problems with mine, turned out to be worn contacts on the slider. I bought a NOS control from e-bay, problem solved