1995 Ford Super Duty on Winnebago

Having a weird problem with AC and this is my best suspect. The problem: When I run the AC hot air comes out.

I am pretty sure that the Heater Water Control Valve is not closing. It is vacuum controlled. When running the AC, the heater core gets hot but the evaporator gets cold too. Looks like they are having a fight and the heater core is winning.

I found this line (see images) that goes nowhere. When I run the engine it clearly sucks air. I stuck a nail in it to plug up the hole and the problem when with the ac went away.

The thing is I have no idea where this thing goes. I have looked around it to find a place that it should go and no luck. BUT if you look at the thing it looks very much like the orange plastic was melted and got sucked into the hose and caused a vacuum leak.

Did it melt or come loose or broke off or both or something else? Is it a service port?

Any help at all is appreciated. Thank you in advance.

 

There was/maybe still, a vacuum diagram on the underside of the hood. If there and readable, it should help trace the lines to their termination points. That engine has loads of emission equip on it. Orange is sometimes a main line from the intake or the vacuum reservoir. If you can see where the line was able to contact something hot by stretching it out ,like exhaust parts, you might find the other part dangling below that location. It might have come from one of the vacuum controlled valves/emission components in that area.

 

Thanks hanky. I will look for a diagram but I think online will hold more promise. This is an RV so there is no hood. It has a dog house and no diagram on the dog house. The images I attached looking from inside the rv down at the the engine.

No kidding about loads of emission stuff on it.

 

Is it possible for you to tell us where the line goes to? If we know at least one end we might be able to tell where it came from. Thanks

 

The vacuum line in question goes along the red line in the image. It runs to a simple device that is mounted to the engine intake manifold, underneath the two large air intake hoses and is boxed in red(it is not visible in the image). The box is much bigger than the device. The device is about 3 inches tall and 3/4 inch in diameter. Beside the line that we are trying to figure out where it goes, there are three more that I have high lighted in green.

One of the green lines goes to a device in the big green box on the right. Not too sure what it does or is called. One of its hoses goes toward the front of the vehicle and ends at the top of a 3in diameter 4in tall can with a hole at the bottom of it.

Another of the hoses from the device boxed in red goes a short distance to what looks like a vacuum controlled device in a small green box and seems to be connected to the fuel rail.

The last line is the long green line that goes down and up to the top of the image. It runs into what I think are the defrost vents for the windshield.

Final note the the image is from inside the rv and the front of the engine is at the top of the image.

Thank you very much for any help.

 

The two large valves you show in the pix are emission controls. One is called a diverter valve and the other is called a by-pass valve.
Both of those valves are vacuum controlled by (TAB) (TAD) temperature sensitive electric valves.
When cold, the air pump, pumps air to the exhaust manifold to complete burning of the exhaust. When a certain temp is reached the vacuum is routed to the diverter valve to now send the air to the top of the converter to assist with cleaning the exhaust. Look for a vacuum line to that valve.
The by-pass valve is supposed to send the air from the pump back to the air cleaner on deceleration to prevent a backfire. Look for a vacuum line to that valve.
There are check valves in the system to protect the air pump and they are known for going bad and allow hot exhaust to get back to the air pump. You can even hear them leak exhaust. I suspect one of the check valves or the piping has a hole and allowed the hot exhaust to melt the plastic line. If you carefully listen for an exhaust leak on the top of the engine when idling you may find the culprit. If you have trouble locating it , try a piece of hose and listen in different areas for the loudest noise.

 

Thanks again hanky

Both of the diverter valve and the by-pass valve have vacuum lines running to them. The top valve has a red (if you care about color) vacuum line running to it from the same device (that I talked about before on the intake manifold) as the mystery vacuum line. The bottom one has a yellow one running to it. Both of the valves also have a hose running to what must be the air pump. I did not see where the intake for the air pump is. Is one of the hoses for air to go into the pump and the other one to go out of the air pump??

I took a pictures of the what I think are the check valves(and included them below along with an overview photo showing where they are). They both run from each of the diverter and bypass valves to the exhaust manifolds. They are connected on the valve side with rubber hose and metal tubing running to the exhaust manifolds.

The problem is that neither what I am guessing here to be the check valves are close to the mystery vacuum tube. But I will check them out for leaks.

 

Great post hanky.

 

Follow up of original problem:
I was able to fix the problem by chasing around the vacuum system lines. I was only curious where the lines went. Among other things I traced a 1/4 diameter hose coming off the exhaust manifold to a 4 inch diameter sphere.

The sphere had only one other hose coming off it which happen to lead to the climate controls and...guess what? ... it was broken. I cut out the broken piece and replaced it with some hose and now the ac works!

The rv uses plastic for the vacuum system. It looks to be a ford thing. While exploring I found another piece of broken plastic hose and repaired that also.

 

Glad you found the fix ! Thanks for the update. When the problems are fixed we all learn something.