Hey whats up. I have a 2001 S-10 with the 4.3L vortec. I replaced my thermostat today and for some reason my heater is still blowing cold air. I just can't think of what would cause this besides the knob being broken or some shit. Anyone had this problem before? It's odd because I would understand the cooling system going out but not the heating. Hit me back up. Thanks guys!