I think I found the module doing it. It's at the passenger side, mounted to the side of the engine compartment, has a plug in it. I disconnected the plug, and the buzz stopped. Obviously it's supposed to be connected. By why is it continuously buzzing.

It buzzes before and after I start and stop the engine. And it doesn't stop. I sat and waited nearly 5 minutes.... it just keeps buzzing. Sounds like a bad solenoid.. but for what?

It's at 0:40 in the video if you want to skip forward.


That's the youtube link

 

Vacuum pump. Might have broken vacuum line to auto 4x4 hubs or hvac system

 

Besides being connected back to itself on each side, it is connected to nothing else. And that big plastic nozzle facing grill-ward is connected to nothing.

I'll search online and see if I can deduce where that goes.

Thanks!

 

It should tee into the vacuum reservoir that sits right next door.

 

 

That helped me isolate and find the issue. I just don't know where the tube goes.

The heater control valve nipple was indeed connected to the stub, however the end of it was just hanging. I can move it to the heater control valve as shown in the video... but the other end of it is pulled off the vacuum system and I can't find where it connects.

Thanks!

 

The vacuum line comes out of the vacuum pump and connects to the reservoir. From there it splits off to the HVAC and then to the vacuum soleniod for the front steering knuckles if you have ESOF.

Here is the normal routing. Yellow line is from vacuum pump to reservoir. Blue line is to HVAC.



Here is by passing the ESOF. Yellow line from previous pic is disconnected. Blue HVAC line is connected directly to vacuum pump.

 

Great pics - that's half the problem. Can you show where the blue line HVAC connection is (the end not shown in the photo)?

EDIT

Actually it doesn't matter. When I disconnect the blue line and hold my finger over it the pump shuts off in a little bit.

That length of tube I found connected to the stub goes nowhere and looks jury-rigged at best.

 

Is your HVAC defaulting to defrost? The lines goes through the firewall to operate the HVAC vents doors. If it is not connected or there is a leak anywhere in the vacuum system it will default to defrost.

 

You can see the black line for the doors/vents. It's the "blue" line from my drawing that goes down to the T off the reservoir. The Gray line is for the heater core on/off valve if you have a Crew Cab truck. The black door/vents line runs down and then through the firewall at the glove box.

EDIT: BTW I'm glad I took these pics. I found a tape measure and some drawings/measurements I had misplaced months ago. Totally forgot I threw them in my glove box.

 

The good news is the fact the pump shuts off means it's working, now just a matter of getting things plumbed back to normal

 

That gray vacuum line at the top - that was connected to the stub at the right bottom corner of your picture. Which I guess makes sense since it's a super cab and not a crew cab.

But the other end of it was just hanging down, going nowhere.

Apparently it's supposed to go through the firewall, and connect to the small manifold in your glove picture? If that's the case, can I just cap that fitting in there? I am guessing that's where the leak is.

 

The gray line goes to the heater core shut off valve in the red box in the pic below. It is only actuated in Max AC mode. To be honest I am not sure in the 05+ if Ford still only put the shut off valve in CC models only or in all cab configurations. I know in the 99-04 MY Ford only plumbed in the valve on CC cabs. It was a popular mod to put one in for other cab configurations.

EDIT: BTW I think the official plug for the gray line if it is not in use is the stud on the heater core box I outlined in yellow.

 

Thanks!

If it was already run through the firewall I think I'd just do that. however it came out and I have no idea where/how to feed it back through. So I think I'll just cap it off at the glove.

 

Would you mind looking at the back side of that glovebox manifold? I ask because mine has three fittings not two.

This part: