I'm getting ready to replace my blower motor resistor and found this video on Youtube. This might be handy for those (like me) who have not had to replace this before, but need to because their AC/Heat is only blowing on high. This is for a 2003 truck, but it looks pretty identical to my 1998. About halfway through the video the guy realizes that he forgot to disconnect the battery, but he does mention that it needs to be done.
FWIW, I searched the forum before posting this and did not find the video already posted, so here is the link.
YouTube - 2003 Ford Ranger Blower Resistor Repair