You have a vacuum leak in the HVAC (Heating, Ventilation, Air Conditioning) system. Inspect the vacuum hoses that operate the HVAC system looking for cracked, pinched or damaged hoses. Also inspect the vacuum reservoir for leaks or damage.
My ac blows only in the defroster and not any of the other vents i have 98 ford windstar 3.8 v6
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The 1984 Buick uses vacuum lines to change air flow from defroster to ac vents. Check the entire vacuum system for leaks.
There may be something blocking the deflectors from sending air up there.
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the middle vents only supply air from the ac unit using a separate in dash fan. the floor and defrost vents come only from the heater
If it blows only out the defroster vents : then check for Vaccume leak Rick ASE L-1 Master TransMichigan.com
Check for vacuum leak either under the hood or under the dash Check the operation of the vacuum actuators Check the selector switch Defrost is the default setting on this system
I am sorry, I am not technical on this stuff, but we had the same problem on our 95 Mustang GT. We had to take it into the dealer and the problem was that one of the hoses had come loose, so it was not blowing enough air pressure to force the vents open.
In a 2002 Ford F-250, if the AC is blowing out of the defroster vents, it could be due to a malfunctioning mode door actuator or a vacuum leak in the HVAC system. The mode door actuator controls the direction of airflow, and if it's stuck or not functioning properly, it may default to the defroster setting. Additionally, a vacuum leak can disrupt the operation of the blend doors, causing air to be directed incorrectly. It's advisable to have the HVAC system inspected to diagnose and resolve the issue.
AC VENTS are in the correct position if they are open and free flowing. Some systems have a heat and an AC position for the vents. The AC position is so the cool air discharges from the vents higher on the walls or from the dash rather than floor or windshield in a car.
The air should be comming out of the defroster vents. If so, most likely, it is the vacuum line that controls the vents. It is on top of the engine below the air cleaner, and runs to the front right of the engine. Buy the replacment so you know what your are looking for.