It sounds as if the drivers side temperature door actuator is stuck in the cold position. To confirm this you will need a scan tool the check for fault codes in the A/C control module of your 2005 Chevrolet Impala.
RepairPal Certified shops can diagnose and repair your 2005 Chevrolet Impala. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.