09 Prostar Outside Temp Display and Direction Icon

The temp sensor for that is actually mounted under the rad near the front right frame rail. Some times it is too close the rad or engine and picking up heat from them. Other than that, it is just a circuit based on resistance. Any change in resistance due to corrosion or a short will alter the temp reading.
There is a bulletin about the compass:
LOCATION

The compass is located in a pocket just above the fuse panel (Item 3 below). The compass can only be mounted in one direction. Check the date code on the module itself. The date code should read 07086. or newer. This is the year (07) and day from 1 to 365 (086). If the date code is older than this replace the module. Check if there are any wires running close to the module that can cause interference. Make sure you have a good connection at the module and none of the terminals are pushed out. There are two calibrations that need to be made calibrate the heading and then the declination zone per the instructions below.