the VAR thing has to do with the compass. if you look in the owners manual you will see a picture of earth with a bunch of lines from the north pole downward. what you do is find where you live, and in between the lines where you live there will be a number. you make the number on the over head console match the number in the book where you live and its suppose to "calibrate" the compass better. thats all that is.
as far as the temp sit, i would agree that the sensor is bad.