why can't i get heat auto control 2009 mercury grand marques

AUTOMATIC When AUTOMATIC is selected: NOTE: If conditions require heat, until the engine is at operating temperature, the blower motor will operate in low and airflow will be directed to the defroster ducts. The air inlet door vacuum control motor is automatically controlled depending on airflow location and desired temperature. The panel door and floor/defrost door vacuum control motors are automatically controlled depending on desired temperature. Blended air temperature is available. The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F). Blower motor speed is automatically controlled. If the fan speed override button is pressed in AUTOMATIC mode, the fan speed will no longer be automatically controlled.

And do what sherrifstech said on your other post.