Juan;

The only real issue that I've had with my car (knock on wood - a '98 S70 base)was a bad thermostat. Your car should warm up to the midrange on the dial pretty quickly...a few minutes even in pretty cold weather. If the needle hangs in the lower part of the range for a long time, think about popping out the thermostat to see if it is stuck or broken open. My thermostat actually had one of the brackets broken right through. Worst part was I thought it was "normal" and drove around way too long like that.

Good luck!