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Big Dave
Big Dave, Shop foreman, Lead Technician
Category: Car
Satisfied Customers: 54
Experience:  6ASE certifications,Electrical,AC,Engine, Steering/suspension,brakes, diagnostics,12years experience
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1996 Buick Park Avenue: defroster..blow..the fuse panel under dash

Customer Question

1996 Buick Park Avenue w/AC; AC works great from the defroster vents and the floor vents; the adjustable vents on the dash will not blow any air; the fuse panel under dash looks good; HELP
Submitted: 11 years ago.
Category: Car
Expert:  Big Dave replied 11 years ago.

Evening Greg

I have some good news for you. The problem is not electrical. The issue you are describing is due to a lack of vacuum to the a/c control head. Usually a vacuum line under the hood gets disconnect or broken, causing a loss fo vacuum to the control head. The air blowing out of the defrost and floor vents is a default mode.

Locating the line is not difficult. By looking along the firewall you can find the small hard black plastic vacuum line that supplies the control head. Follow it to where it is broken or disconnected. Repair with a small piece of rubber vacuum line and/or reconnect to vacuum.

Feel free to post again if you need further assistance with this.

Thank you


Customer: replied 11 years ago.
Reply to Big Dave's Post: looks like the engine compartment vacuum line is okay; I dropped the glove box and can see a white plastic arm that moves slowly as if vacuum activated; where does the vacuum line attach at the interior of the car OR should I still be looking in the engine compartment [the line is the one that is tapped off the brake vacuum assist, right?]
Expert:  Big Dave replied 11 years ago.

Evening greg

The vacuum line goes from a vacuum source in the engine compartment to the a/c controll head. Remove the control head, and disconnect the vacuum harness on the back of the control unit. There should be vacuum to the black line while the engineis running. If not follow that line and look for the break or the lack of connection.

With no vacuum there is no function. If there is vacuum we can check the individual vacuum motors. We need to start at the beginning. and it allstarts with a vacuum supply.

Not exactly sure where the line is. I dont have the diagrams in front me. I am doing this from memory.

Let me know what you find.


Customer: replied 11 years ago.
Reply to Big Dave's Post: Thank you for the reply! I only just now got the message. Is the AC control box in the interior under the dash? What is the best method to remove it? I will pay for your help if it helps me make the repair.
Expert:  Big Dave replied 11 years ago.

Morning greg

First thing you need to do is remove the shield underneath the passengers side of the dash. Once you have that removed you gain access to the vacuum harness connector. remove the connector start the vehicle and listen /feel for vacuum at the black hose.

Thank you