Chevy Venture HVAC problem

I know that a Chevy Venture is a minivan, and not a truck. The minivan is my wifes, and I drive a Dodge Ram. I had to preface this, because I did not want to insult a fellow pickup driver. There is not a minivan forum, and also pickup drivers are more hands on and knowledgeable than car drivers. My wife has a 2000 Chevy Venture. The problem is that the HVAC is only blowing out the floor vents, and not the dash vents. The blower runs fine at all speeds. The AC is cold, and the Heat is Hot. The mode knob (The knob that controls Dash Vent, Floor Vent, Mixture dash/floor, floor/defrost, Defrost) has no effect. After taking apart the dash, and the Haynes manual; I learned this is controlled with vacuum pressure. I can manually switch the vents using the mode actuator which has the vacuum lines from the knob. So I'm guessing the door that directs the airflow is not clogged or stuck. There is nothing blocking the vents, as I ran fishtape with a rag throughout without obstruction. Also, the cabin air filter is fine; and I even took them out for maximum flow to diagnose. The vacuum lines apparently go somewhere into the engine (Intake Manifold?) The Haynes Manual does not do a good job of explaining this (Surprise on that one,) And the engine compartment is so tight, and the engine sideways that I can't find where the vacuum lines come out of the firewall, and into the compartment. I also didn't mention that when disconnecting the various vacuum lines, I did not feel any pressure in or out. If I did feel any pressure, then I wouldn't be sure how much I should feel. I don't have a vacuum tester. I am guessing there is a vacuum leak somewhere from the firewall to wherever the vacuum line connects to in the engine compartment?

On the lighter side of things: The window spray hose that goes to the rear wiper was disconnected in the engine compartment. The hose is the same size as the vacuum lines, and appears to go through the firewall. After noticing it disconnected, I was jumping for joy; and told my wife I fixed the problem. I turned on the Van to test the problem, and as you guessed the problem was still there. I went back to the engine compartment thinking that maybe the hose was clogged from being disconnected. I followed the hose to the washer resevoir. Boy, did I feel stupid. At least I fixed the rear wiper washer, and this did make my wife happy!

Thank you in advance to anyone who reads this! If you don't have any ideas, then can you please tell me where the in the engine compartment the vacuum line runs.

Reply to
Xclimation
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If it is vacuum controlled it is likely a leak UNDER the hood. Simply because of the heat/cold conditions there. Look on the pass side it should be there somwhere. You could also listen for a leak with the engine idling.

Reply to
ShoeSalesman

Found the problem, and fixed it! It was the vacuum hose under the battery. The hose is within a wire harness that runs through the firewall, and the vacuum hose splits out of the harness after some traveling. I had to undo the harness to find where the hose was melted.

Reply to
Xclimation

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