99 3500 24v 190k 5sp 2wd

For about 4 months the temperature gauge has not moved in the cabin. It is all stock. Never cared about it, it is always at least 80+f here and the humidity is just as bad. No water leaks, does not overheat, use the a/c most of the time. Have gone on 3K trips quite often up and down mountains, nothing.

Yesterday, bought a 190 thermostat, all ok, but the gauge does not move. Infront of the thermostat housing is a wire that connects, took that off, cleaned it, nothing.

Do I have to worry? I don't want to mess with something that just might be cosmetic. Appreciate your input.