i have a 2000 buick lesabre custom and today my heater quit. the blower fan works fine but all it is doing is blow cold air on my heater setting. the lesabre owner manual states the the thermostat temperature should be 195 degrees F but i noticed that after driving for about 20 miles the temp guage showed only 185 degrees F. would this have anything to do with the heater not working. the outside temperature was about 40 degrees F. or is there other problem associated with the heat not working? any suggestions will be appreciated. thank you.

 

My bet is your thermostat is stuck open. You could also have a stoppage in your heater core, but most likely the thermostat is the culprit. It should be pretty easy to get to right on the front left of the engine. Let the car get good and cool and then pop the housing off. If you can see daylight through where the seal is then replace the thermostat. This isnt a definative test, but it is a good place to start.
Hope this helps ya,
Billy

 

I had an 89 Jeep Cherokee without heat and the blower worked fine. Turns out that the heater core needed replacing. Good luck with your car.