DaveP
Active member
Re: Hvac gurus needed
You've been struggling with this for two weeks. I can't take it anymore. Too agonizing to watch.
Are you CERTAIN the HVAC vacuum line in the engine compartment is hooked to engine vacuum? In the vacuum diagram Nate posted above, the HVAC line is at the top right. Note it is on the vacuum ball side of the check valve.
This line comes out of the blower wiring harness about 4" from the firewall. This harness comes through the firewall right behind the distributor. If this hard line breaks off flush with the harness, which they do, and you don't know where to find or look for it, you'll never find it. Now that someone has told you where it is, is it hooked to engine vacuum?
Inside the truck: The black vacuum supply line comes into the truck as part of the wiring harness. I may be wrong, but I think that the color of the hose from the controls to the single main-line junction is grey. After the junction, it becomes the black hard plastic. This single-line junction is clear in color, and about 18" in from the control head. There is a multi-pin wiring connection at about the same place, 18" from the controls. There is another mufti-circuit vacuum connection from the controls to the inside vacuum dash-pots. All of these need to be connected, but concentrate on the grey-to-black single line main vacuum source.
I doubt you'd hear a hissing if this junction were open. The "hiss" people are referring to is when you change the mode selector positions. You hear an audible hiss as the vacuum pots release.
You should be able to see the single-line supply junction by looking into the hole behind the controls, knowing that it is there. See if it's hooked up. It probably is. You can probably reach it best by removing the instrument cluster, and perhaps the surround. I'm not sure. It's pretty far back there. I connect all three of the HVAC junctions with the entire Inst Panel still in my lap before putting it up on the hangers.
If you need to get to this junction, post back, and I'll tell you the best way to tilt the IP backwards away from the base of the windshield, and you can reach the junction over the front edge of the IP. Shouldn't take more than 45 minutes to do the whole thing. But you have to know the tricks.
I think you've missed the vacuum connection in the engine compartment. 4" from the firewall, 3/32" black hard plastic line. Has a rubber molded-on elbow on the end. If it isn't there, cut the harness open and find it. Because that's your problem.
Pleas post what you finally find was wrong. This info should help.
You've been struggling with this for two weeks. I can't take it anymore. Too agonizing to watch.
Are you CERTAIN the HVAC vacuum line in the engine compartment is hooked to engine vacuum? In the vacuum diagram Nate posted above, the HVAC line is at the top right. Note it is on the vacuum ball side of the check valve.
This line comes out of the blower wiring harness about 4" from the firewall. This harness comes through the firewall right behind the distributor. If this hard line breaks off flush with the harness, which they do, and you don't know where to find or look for it, you'll never find it. Now that someone has told you where it is, is it hooked to engine vacuum?
Inside the truck: The black vacuum supply line comes into the truck as part of the wiring harness. I may be wrong, but I think that the color of the hose from the controls to the single main-line junction is grey. After the junction, it becomes the black hard plastic. This single-line junction is clear in color, and about 18" in from the control head. There is a multi-pin wiring connection at about the same place, 18" from the controls. There is another mufti-circuit vacuum connection from the controls to the inside vacuum dash-pots. All of these need to be connected, but concentrate on the grey-to-black single line main vacuum source.
I doubt you'd hear a hissing if this junction were open. The "hiss" people are referring to is when you change the mode selector positions. You hear an audible hiss as the vacuum pots release.
You should be able to see the single-line supply junction by looking into the hole behind the controls, knowing that it is there. See if it's hooked up. It probably is. You can probably reach it best by removing the instrument cluster, and perhaps the surround. I'm not sure. It's pretty far back there. I connect all three of the HVAC junctions with the entire Inst Panel still in my lap before putting it up on the hangers.
If you need to get to this junction, post back, and I'll tell you the best way to tilt the IP backwards away from the base of the windshield, and you can reach the junction over the front edge of the IP. Shouldn't take more than 45 minutes to do the whole thing. But you have to know the tricks.
I think you've missed the vacuum connection in the engine compartment. 4" from the firewall, 3/32" black hard plastic line. Has a rubber molded-on elbow on the end. If it isn't there, cut the harness open and find it. Because that's your problem.
Pleas post what you finally find was wrong. This info should help.
