I have an 04 Concorde that is intermittently not turning on. I always have it on high, and I noticed that it didn't turn on when I start the car. I've read other threads about the same thing, but one thing I haven't seen covered is that when it's 20 degrees outside in the morning, the fan does come on and run correctly in all speeds. After that driving to work and sitting all day, it won't come back on. One time I smacked the area where the resistor is and it came on, but it ran unevenly all the way home. It hasn't helped to smack it after that one time. I'm getting ready to order a resistor and a fan motor/squirrel cage assembly, but I wanted to see if anybody can enlighten me about the working when it's cold thing.

 

15 yrs old, metals tarnish, electrical current heat over time can also allow spade connectors of wiring to expand. COLD thin metals tend to CONTRACT, thus giving you good connection...until things "warm up".
Good Luck and let us know how things get "spinning"!