Yesterday I had to replace the battery in my '02 Avalanche. After doing so when I started the engine I noticed that my heater controls were only allowing air to come out of the dashboard vents, therefore no air for defrost, floor etc. Turning the directional controller knob has no effect on air flow. This vehicle has the auto temp control as well but in this mode or manual mode there is no difference. Is this the result of disconnecting/reconnecting battery or just a coinsidence and does anyone have thoughts on fixing.