Door sensor

Hi,
I have this problem with the door sensor in my Taurus '01. If it's cold outside it's fine. When car is getting warmer from the sun, the sensor that is in charge of door (driver door) starts to show that door is still open, despite the fact that it's closed. That in turn causes the car to 'warn' me that something is not closed when I want to lock it with the remote. When it cools down it doesn't behave this way. I know it's kind of a problem you can live with, but it gets very annoying. Does anyone know what needs to be changed and how to do it? I suspect it's a sensor, but I would like anyone to confirm and point me what should I disassemble in order to get to it.
Thanks in advance for your replies.

Andy

The first thing I would do is pull the switch for that door and see if there are any loose connections. Maybe even trade that switch with one from another door and see if the problem shifts to the traded door or stays in the same place.

Spray the door latch liberally with penetrating fluid. The door switch is on top of the latch mechanism inside the door panel. These are a known Ford problem.