Technical Car Experts Answers everything you need: dodge cummins vacuum lines

Ford Windstar HVAC system not working and hissing noise under dash is heard need vacuum line diagram to inspect vacuum leak issue

The system is blowing warm air out of the dash vents and the rear air will only blow from the bottom outlet

First inspect vacuum control switch,if its faulty,then replace it.

If problem same even after replacing vacuum switch,then other possibilities needs to be checked inspected.

1998 Ford Windstar 3.8L

NOTE: The vacuum source is the intake manifold feeding the vacuum reservoir and the A/C picks it up from there,

See below i have mentioned the diagram for the system, also there is an electronic actuator that operates the temp blen door, you might want to look at it.

Vacuum Control Diagram

Ford Vacuum line diagram

Item Part Number Description
1 19850 A/C Evaporator Housing
2 - A/C Evaporator Core
3 18A318 Heater and A/C Air Inlet Duct Door Vacuum Control Motor
4 18527 Blower Motor
5 18476 Heater Core
6 18C581 Vacuum Hose Harness
7 19A566 A/C Vacuum Reservoir Tank and Bracket
8 19A563 A/C Vacuum Check Valve
9 18A318 Windshield Defroster Door Vacuum Control Motor
10 18A318 Heater Air Damper Door Vacuum Control Motor

When on panel, it is the outside air along with the heat from the engine being pulled into the cabin, that's the difference,The vacuum source will come from the upper intake manifold on the passenger side rear, it will be an elbow with 2 lines attached. The black line shown in the diagram above is the vacuum canister feed.
There will also be a black line running into the fire wall that feeds the A/C door motors.
If the compressors not coming on then you need to check for power at the cycling switch, or take a jumper wire and jump the 2 terminals and see if the compressor cycles on, is there a full charge of freon in the system?
I believe you got more than 1 problem here, start with the cycling switch first and the Freon level .,
And continue further troubleshooting to correct the issue.

These details will help.
Thanks.

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Its \behind the radio.
You don't need to pull the radio or take half the dash apart. The connector is lower down, on the same level as the gas pedal but in the middle of the cab. It's got maybe 8 vacuum lines on each side, all different colors.

See the diagram below :----

In many case when Ac only blows through defrost vents.You need to inspect this vacuum line/.

Pull the supply line off of there,its a red vacuum line, start the engine, and see if you've got vacuum.There is one more line that is black one.

Try the black one (the lower one in your picture).

For that you have to pull the glovebox door off. Once the glove box is out you can easily reach in back by the firewall side, and find the hose where it comes in with the A/C lines.Pull that hose back and forth from one side of the cab to the other, to make sure you are checking inspecting the right line. Once you confirm its correct line ,then disconnect it off of the vacuum connector,you can see that in the picture shown above, and see if there is no vacuum with the truck running. Then get under the hood and pull it completely out through the firewall. The bad spot sometimes is very minor so pull the line completely out,to get complete idea. Because you can't really get to it with the dash installed. There can be small spot where the hose connects or a pinched line, probably about 4" back from where it comes through the firewall.

After that inspect the supply line back over to the vacuum pump. Before it goes into the pump, it goes into a large Tee with a couple other vacuum lines and plugs. Move some of the plugs around, and put it back on a different spot (closer to the driver's side). This allows you to run the line right through the grommet on the driver's side firewall, rather than across the engine compartment, into the cab, and back across the dash.

This basic details will help you.

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