I have a '97 Dodge grand caravan Le, when it starts to get cold out, November thru the winter the hatch won't open.. it won't open with the key either.. there is nothing in the way and have looked for something that could be the problem and can't figure it out.. does it only when it gets cold.. temps of 20 degrees to below zero. I am stumped..

 

sounds like the strong arms on the hatch (the two black rods on each side) are probably worn or even rusted at the ends, mine has the same problem especialy when its cold but luckily only one of mine are worn and can still get the hatch open (i realy have to pull hard to open it and there is no chance i can let the kids open it since it is so hard to pull)

 

It won't open or unlock? If it flat out won't open then the key has nothing to do with it. If it doesn't unlock, I know my van has needed lock lubricant on the rear hatch before which makes it much smoother to unlock.