So, my temp guage is acting funny where I can be driving for a half hour and it will not move, then all of a sudden it will jump to normal level, half way and I will regain heat in the car. Then it will go back down and it will pump out cold air. Does this seem like it could be a stuck thermostat? It is below zero here in Chicago. However, the thermostat is relatively new, probably a year or so old.