All of a sudden the AC/heater fan on my 2004 Toyota Matrix does not work properly. The fan has four positions. The first 3 no longer blow air at all, but the 4th position (the highest) works. A friend of mine said the blower motor resister is bad. Does that sound correct?
Your blower motor resistor module has blown. The fourth position provides 1:1 (full 12v) power to the fan. The other three positions provide reduced power, which allows the fan to operate at lower speeds. You can buy a replacement part relatively cheap online. This should be fairly easy to replace as well. It should easily be found under dash on the passenger side by removing any coverings in the foot well area. It should be located to the left of the fan motor assembly and should (besides the motor) be about the only thing with wires attached to it.