cant get AC to go thru upper vents

[JohnsRed79]

Hello everyone................My AC only comes thru the lower ducts toward the floor. What steps or is there a diagram I can look at to see how to get the AC to come thru the upper ducts......I know there is a diverter that is supposed switch it back and forth that uses vauum pressure......I have a 79......... Thanks John

 

[Bob Chadwick]

John,

When I had the same problem I found that the problem was either related to vacuum getting to and out of the control head and out to the actuator to the left of the air diverter in center of the dash or a bad actuator. You are going to take a look at these areas and try and troubleshoot the problem. My web page has a lot of information including a vacuum diagram put together by VMRod.

It's been a long time and I had it all apart at the time so I can't recall if you can get to that actuator with the dash together but if you can, I would pull the vacuum line off the actuator and play with the control head and see if you get vacuum to the line.

Mine turned out to be in the control head so I didn't play with the actuator much. There are actually three positions to the air diverter; floor, vent and defrost. I'm not sure how the actuator knows to stop in the middle unless when you set the thing to vent another vacuum line comes into play and somehow puts a "stop" in position limiting the movement to halfway.

Hopefully someone will have additional information to help you but I think you got enough here to get started.