Mercury Grand Marquis AC only blows out of defrost, not from vents on Mercury Grand Marquis

Some Mercury Grand Marquis owners report experiencing issues with their AC systems, specifically that air only blows out of the defrost vents instead of the regular vents. This problem may be attributed to a faulty blend door actuator, which controls airflow direction and may require inspection or replacement. Additionally, some owners have found that leaks or blockages in the vacuum lines can restrict airflow, causing air to be directed to specific vents only. Problems with the temperature control system can also contribute to these airflow issues. If these potential solutions do not rectify the situation, it is recommended that owners seek a professional mechanic's assistance for a thorough inspection and diagnosis of the AC system.