I had a problem with the battery going dead on my 2004. In my case, the A/C & heater blower motor continued to run after the engine was turned off and the key was out of the ignition. It turns out that is was a faulty blower motor resistor, which is bolted on to the blower motor and accessible through a removable panel inside under the glove compartment. The crossfire part is expensive, but I was able to buy an equivalent replacement part for a Mercedes CLK320 for around $65 shipped.