The second and most used speed on my blower does not work do I need to replace the switch?

no there is a piece under dash near blower motor called blower motor resistor block it can be purchased from napa or any other aftermarket realy a simple fix

Bruce, I am having the same problem with my Ford truck. This is just what I was looking for as I didn't know just what I need to do to fix the problem. Thanks, Paul

If your 06 explorer is like the 04 ranger I used to have the resistor is besides the blower motor,witch is on the right side of the firewall under the hood,1 plug in and 2 screws.5min job.

at the time at napa if I remember well the resistor was around 26$.