I have a '92 Saab 900s that has a problem with the heating system. While driving the vents produce a warm flow of air but not enough heat to warm the car. While idling the vents do not produce any heat. I have also just recently noticed that the thermostat gauge is not centered but instead reads half way between centered and cold. The coolant level is fine but maybe 3-4 times this year I have had to add a small amount to the system. Are there any ideas of what may be wrong with the heating system?(posted 8860 days ago)