A/C Not Blowing out Vents

[jlasinski]

I have an recently aquired a 1985 GN with the automatic climate control A/C. It seems to blow cold but only out the defrost and bottom vent. There are some vacuum lines hanging there on the passenger side inner fender that are probably the problem. Does anyone have a diagram that shows the line routings for this system and have any advice in gettin gthis working? Thanks, John

 

[klmnla]

Mine was doing the same thing and ended up being the round vacuum selector switch on top of the AC control. I had to slide the AC controls out the dash, remove and repair the switch with JB weld and a washer. I later discovered that advance auto sells the switch unit fairly cheap. Others will suggest checking the blower door behind the glove box.

 

[just plain john]

There's a diverter door that works off of a vacuum signal. If it's not getting vacuum, the door remains open (or closed), which sends the air out the vents or the floor. Where are the loose vacuum lines, drivers or passenger side?

 

[jlasinski]

They are on the passenger side. One is coming out of a black cylinder (very small diameter hard line) and the other looks like maybe from the firewall (rubber hose, maybe 3/16" diameter) Thanks, John

 

[just plain john]

I replaced all the interior vacuum lines recently. They are color coded and have factory molded connectors. There's a black plastic plug that penetrates the floor below the A/C box. Two hard black lines leave it and go underhood, one goes to the heater control valve, the other to the vacuum ball reservoir. The line to the ball is the vacuum source for the A/C controls. Since you say the A/C works but the diverter doesn't, check on the drivers side under the dash. There's a large diaphram with 3 hoses connected to it. Make sure all 3 are connected and report back.