I have a 2002 S60 AWD. Love the car and have had since 2005. Current issue is that with doors locked, the key will not turn in the lock. The key fob will open the doors, so the it isn't the actuator. We haven't had any rain or snow, but it is cold. The car had been in the garage for the last 4 days. I've put it back in the garage and will see if warming it up makes a difference. Any other thoughts?

 

If you aren't having a similar issue with the ignition it's probably a worn lock cylinder.

 

powdered graphite first.
Then maybe a new cylinder?