Just purchased a 2000 Jetta and the car will not get up to the 190 operating range. The needle will barely get to the mark below the 190 reading on the gauge in the dash then promptly falls back a little. This is also coupled with the fact that there is no heat blowing into the interior of the car. Would a simple thermostat replacement fix the lack of heat issue, or is there something more to it?[&:]

 

You do need a new thermostat.