Temperature gauge doesn't move on 1990 Ford Escort

Why doesn't the temperature gauge move. I replaced thermostat and some heat comes out but gauge doesn't move.

Asked by for the 1990 Ford Escort
There could be a few reasons for this. You may have a problem with the temperature sensor, wiring or the temperature gauge, but it will take someone who can diagnose this electrical circuit to know for sure.
It is a sender in the thermostat housing. It went bad on my car. easy replacement