Howfreezinh to stop lock on chrsyler sebring ?

The drivers door on my sebring is frozen each morning. The lock is keyless and I use the remote fob to try and unlock the door when i do this the button inside pops up as if the lock has opened but the door will not open from either the outside or inside. The problem fixes itself after the temparture rises. I have sprayed all parts of the locks which i can see without removing the door panel but this hasn't made any difference. Anybody got any idea how to fix?

Baz
December 2010