blower motor or electrical problem

[TheProfessor]

the blower motor for the heat in one of my rettas works like when it wants to has no pattern to it at all
sometimes ill have it on high and it will just kick on after 10 15 mins of driving sometimes not
does this sould familiar to anyone
i really dont want to go outside and trace shit down with the DMM in the cold

[korbendallas68]

Blower motor resistor. Located near to the blower motor on the firewall. Very cheap and easy to change.