AC vacuum hose under dash on 97 ford van

Check this images and parts mentioned in the images, that will help:----

The linkage and the vacuum operated actuator are circled...


Does the actuator move when you hit it with vacuum?

Well you can physically move the lever to see if the actuator is locked up for starters.

And then you can start the truck (to get a vacuum source), and run a new line from a known vacuum source to the actuator.

Or you could buy a hand pump.

i had a vaccume line knocked off behind the dash, take out the ashtray and ac controll panel and the glove box and see if you can hear a leak or see a tube that is not connected. mine was a yellow hose behind the ashtray that was knocked off of a vaccume actuator. i put it back on and was good to go.

My a/c has been pissing me off like a crazy. It blows cold for a while until all of a sudden it starts blowing in the defrost mode. I looked at that white plastic line and when I gently touched it it crumbled in my fingers, lol. I guess I know the source of the problem now.------

White vacuum line:

Embilical that it runs into:

Where it runs into the FireWall:

Found it behind the glove box:

This is what I found running from the direction of the firewall:


i went outside and i pushed in the motor under the hood that the white line goes into and it didnt switch the a/c or anything, stayed the same. does that mean anything? vacuum lines are so confusing!

about the outside door vacuum motor under the hood.
If the diaphragm is bad in the vacuum motor then yes that would be the same a broken white vacuum line.

Why the white vacuum line causes this is it lets air in and then you have no vacuum. It has nothing to do with the position of the vacuum motor in or out.

You are moving the vacuum motor by hand under the dash and that will tell you nothing.
You need to put a hand vacuum pump on the lines of each vacuum motor and see if they hold vacuum or not. Also see if you are getting vacuum on the black vacuum line with the gauge on the vacuum pump.

You can rent a hand vacuum pump at most auto part stores.

Do not use a propane torch or other sprays for finding vacuum leaks on this vent system, they are for checking the the engine gaskets.

As the diagram shows the vacuum line runs from the vacuum tree on the upper intake to the vacuum check valve.
From the vacuum check valve it goes to a "T" and from there one vacuum line goes to the vacuum tank on the side of the heater box.
The other black vacuum line from the "T" goes to a inline vacuum splice and then a hose and another inline splice and then it goes to the vacuum selector control valve on the dash.

Now you go to an auto parts store and rent a hand vacuum pump with a gauge on it. When you take it back you get your money back or you can buy it as it does not cost very much.

Check the vacuum line from the "T" to the vacuum tree on the upper intake manifold and make sure it is OK.

Now unplug the vacuum plug off the vacuum selector control valve on the dash, the one with 5 vacuum lines on it.
Put the vacuum pump on the plug nipple that has the black vacuum line on the other side. Pump up the vacuum and see if it holds. If it does not hold then work on the vacuum lines back to the engine.
If it holds vacuum then pump up vacuum on the other nipples one at a time until you find the one that does not hold vacuum and fix the vacuum line or its vacuum motor.
If all the nipples hold vacuum then replace the vacuum selector control valve on the dash.


the bottom part goes into the cab to the air conditioning stuff, and the top part goes into the vacuum tree.

The left part goes to the vent system vacuum reservoir.
That "T" is also a check valve.

well im pretty sure i foudn my problem. i found a vacuum door or actuator. whatever their called under the dash next to the glove box. i turned on my ac and pushed it in and it started blowing out my vents like its supposed to. so im assuming its that blue line that goes to it or could it be that thing itself? anyways the line goes upbehind the dash and im having a bit of trouble tracing its path. i know it eventually plugs into the a/c control panel but before that im not too sure. am i going to have to pull part of the dash off for this one?

I do not think the blue vacuum line or the vacuum motor is your problem. BUT still check the image below:--


I have never hear of that blue vacuum line or its Panel Door vacuum motor going bad.
As said above most of the time it is the white vacuum line going to the vacuum motor on top of the heater/AC box that has a break.

One end goes to source vacuum (intake manifold or vacuum port) the other goes through the firewall to the vent control.Once you splice them back together your vents will work again

dealing with the A/C pipes, heater hoses, vacuum hoses, mounting stud nuts under the hood and mounting bolts inside. Once the box is moving, the dash needs to "get floppy" so you can pull back the passenger side far enough to give the main HVAC box enough room pull away from firewall, and to "roll" back towards you. At this point the heater pipes will be visible,

No comments:

Post a Comment