well when i first bout my jeep six month ago
i only drove it a few times but i remember the temp
gage moving allot "bouncing" so i knew there was a prob.
well now that I'm all most done with the jeep i need it working
right. i picked up a new temp sender and a fan clutch.
so the gage just reads cold and doesn't move now, and when i turn the key to the start position the gage pegs out to the hot and then goes right back down and doesn't move.....what do you think is wrong?

 

Bad connection somewhere. Gauge to cluster wiring/connection? If all other gauges work correctly and since you replaced sending unit, it could be in the gauge itself.