Htr / Air controls do not shift the vents - Vacuum issue?

[John_S2]

The heater / air conditioning vents seem to be stuck in the defrost setting even when I turn the control knob to Vent or air conditioning, etc.... I do not hear the normal vacuum sound when I move the dial like I normally do.

Is there a vacuum hose somewhere that may have gotten disconnected?

I opened the hood of my 1999 Ford V10 engine but I do not see any hoses that look like they are for the heater. I did not remove the air cleaner pieces to look under/behind them.

Are there any hoses under the dash itself or in the dog house area?

If not a loose hose is there some other thing to suspect or check out.

The blower and everything else seems to be working.

Would appreciate any and all suggestions.

Thanks, John S.

[j-d]

Since we'd be hunting for space to put a Tank where there isn't one already, I'd suggest this one for $13 on Amazon. I used this "two way" check valve, meaning it served as a Tee and a Valve.

There's another Dorman Vacuum Tank that might have the Check Valve built in. I chose the one where I could use a separate valve that incorporated a Tee (to supply the Tank and the HVAC Controls). Either way, it takes a Check Valve, a Tee, and a Tank.

Tank is pretty large. Check Valve has to be first. Engine vacuum source, then Check Valve. Then the Tee. One line from Tee to Tank, other line from Tee to HVAC Controls inside the cockpit.

[Pirate1]

Mine was colapsed. Replaced, fixed issue. Mounted almost under front bumper area (if you had a bumper).

https://www.ebay.com/p/Ford-OEM-EGR-System-vacuum-Reservoir-Canister-Tank-4C3Z9E453AA/1211111806

[j-d]

This IS the simple solution. If a dealership follows the manuals, it's an invasive, expensive project from standpoints of both Parts and Labor. But mostly labor.

The job is not as hard as it might appear from my detailed write-ups. Any relatively handy person can do this. Say somebody who can replace a drive belt on a lawnmower, change oil/filter on a car, change a flat tire...

Can you post photos?

If you can, take two and post them:

1. Passenger Foot Well: Straight Forward from the Seat, to take in the firewall with the metal servo and a couple hoses. Hoses are thin Plastic Tubes, Black and White

2. Passenger Side of Engine Compartment: From Fender to Center, From Hood Gasket Edge down to include part of the Battery.

If you can't, I'll go take a couple and let you see if they match what you see.

We can do this!

[John_S2]

Yikes, I was hoping for a simple solution for this problem as I am not very handy when it comes to mechanical/auto repair issues and will have to rely on somebody with a lot more experience and/or technical ability.

If it is indeed something like this vacuum reserve tank and check valve needing a complete replacement and bypass who do you suggest I have tackle it? Should I stick with a Ford dealership or is it possible to save some money by going to a decent auto/truck repair shop? If ford was quoting $900 in labor back in 2015 I hate to think what they are quoting/charging today.

Appreciate any and all suggestions. Thanks again, John S

[j-d]

Many of us have run into this issue with various Fords. Some engineer got the bright idea to put the A/C Vacuum Reserve Chamber and Check Valve INSIDE the HVAC Cabinet. I have two threads that shows how I fixed ours. It's easy and inexpensive.

My thread on RV.net Class C

Lengthy Thread on BATAuto.com

Long and Short of it is This:

To diagnose it and quickly get to what took me HOURS:

1. Get some 5/32" Vacuum/Wiper Hose

2. Find the RED "hose" (actually plastic tubing) near the Transmission Dipstick and the HVAC Accumulator (black metal can coffee sized). Should join to Black at a connector you can pull. With engine idling, feel for vacuum on the RED end. Got Vacuum, Right? Re-Connect to Black

3. Go into the passenger side foot well, and look forward to the firewall. Find the BLACK plastic tube. Cut it, leaving a couple inches where it comes out of the plastic HVAC Cabinet.

4. Engine idling, feel for Vacuum on the ends of that cut hose. If the problem is what I think it is, you will NOT find vacuum.

5. No vacuum on that cut hose... You need to do two things now:

6. Bypass the vacuum system from where you unplugged Black from Red under the hood, to where you cut Black inside.

7. Provide a Check Valve and Reserve Tank to keep the A/C controls working when you open the throttle and engine vacuum drops.

The threads show the common Dorman part numbers I bought. With the Check Valve, the Tank, and the Vacuum Hose, you can do all that. Cut the Black tube under the hood beyond the connector to Red. Connect the Dorman Tee Check Valve there, and run one side of the Tee to the Tank.

You can get the hose down into the fender, toward the door post. Then find and poke a hole in a grommet in the door post. Pull the hose through and connect where you cut.

There are various places to hide the Tank. I put mine under the hood, behind the air filter, where I found a couple little brackets. There IS a tank with the check valve built in. I chose to hide the tank, hope it'd never fail, and put the check valve where I could easily change it. I've had to replace it once already.

Let me know if I can help.

[imgoin4it]

Sounds like a loss of vacuum probably hose off or broken. Defrost is the default position.