RIGHT AFTER OUR BATTERY WENT DEAD AND HAD TO BE ...
2003 Chevrolet Trailblazer
November, 2, 2012 AT 3:14 AM
Right after our battery went dead and had to be replaced, cold air started blowing out at our feet when set for upper vents only when we had the air conditioner on. We have already spent $323.00 on this and it still does it. Our mechanic said some law passed in 1975 says there has to be air blowing all the time but I would think that is for when the system is off.
The electrical system made have to be reset. Try removing battery and hooking pos. And neg. Cables together, while battery is removed, and let sit overnight. Put battery back in car, put cables back on correctly, then drive car for a short distance, to let ecm relearn. Then try a/c and heat again. If still blowing out at feet when on vent you probably have a vac. Leak, on supply line to dash.