The heater in my '07 Sonata (V6) does not seem to do too much - the air gets warm, but not hot - even at full blast. (A real problem here in Wisconsin when the outside temp gets below zero). Temperature gauge always reads below the mid-point on the gauge. My hunch is I need to install a hotter thermostat, but anybody got any other ideas? And is the thermostat on this engine where the upper radiator hose is connected to the engine? Thanks to anyone who answers!