Dash A/C vs Max Air Setting Question 2008 Sightseer 29R

[7997redtail]

I thought i had posted this question already but cant find it sooooo. Age problem i think.

I have had the AC checked and run on the latest AC unit and whatever else they do. All the numbers when it was worked on were correct. On Max AC we get good cold air but nothing like my Jeep. On AC it doesn't do anything at all.

Originally it was cold but worse than Max ac. It doesn't have any leaks and I expect everything is good with the fluids and piping.

An AC guy at work gave me a few things to check. The first was to turn on each mode and ensure the clutch is engaging. It does in both modes.

He said if the clutch engages it might be something behind the dash. Part of this reasoning is that it passes the AC service machines functions.

So my questions are

Do any other F53 2007 ACs work poorly on just AC?

What might be behind the dash that would affect the cold air on just AC (my buddy is on holidays)?

Im going to keep on research while I wait for all the experts here mull this over.

Thanks in advance.

[Morich]

Simple thing that most of us can spot?
Can you spot a radiator line that goes from the engine to inside the big cover where the blower pulls air in to pass it over the heater?
There may be a valve in one of those radiator hoses that should open and close, depending on if you want heat or not!
The AC may be working fine but if the heater is still heating the air before it gets to you, you can't tell it's doing anything!
On older it was a simple wire from the dash to the valve and you could see if the wire moved the valve! This is one operated by vacuum line:
https://www.ebay.com/itm/13406317743...d48747c6d56d2c

Possible you could spot it and make sure it is still moving to open and close the hot water going to the heater?

[7997redtail]

So often I read your (and a couple other smart people on this site) responses and see those odd things that only someone who really knows this stuff comes up with.

I’ll try to get a look in before the hockey game or it’ll tomorrow afternoon. I gather the valve shown can be either vacuum or electric so I’ll look for either. Shouldn’t be too hard to spot (I guess I shouldn’t have put that in) .

Thanks for the reply

[Morich]

Before you give the idea too much credit, keep in mind that is may be a way old and way late idea!
It's one of those things that is easy enough to look under the hood and maybe it's there or maybe they have stopped using it ten years ago!
Good luck with the search!

[7997redtail]

The game starts in a few minutes but here is what I’ve found.

I can see two distinctive valves although the Win. drawing show three.

One is called “engine driven” so I’ll exclude that.

The second is on the right side of the box. I’m guessing it might be fresh reserc. ?

The last one looks like it might be it. It’s described as a “water valve vacuum control new design”.

I’ll do some research on how to test them and this can be step #4 of solving the problem.

[Morich]

OK! I got some ideas on the first one as I know it a bit!

I think I see a black tube running as marked in red and that is where the engine running makes a vacuum on that tube. I might think the tube has a central point where it may connect together with some other tubes on a fitting of some type.
Maybe something that looks like a plastic "tree" with different tubes on each limb of the tree. Maybe a "manifold" if that is a thing you know about?
What I think is when the engine runs it makes a vacuum and this tube may connect to the heater controls that are then connected to the vacuum.

Testing can be kind of simple if we have the engine running and get the tube off this valve thing, we can put a finger over the tube end and feel it suck on our finger if there is vacuum there! Knowing where that vacuum comes from so we can set the control that cuts the vacuum on and off may be a guess that takes some looking??/
But the idea is the vacuum pulls on the inside of this valve and makes the lever on the side move up and down. that moving moves the flap inside that changes where the air moves. Maybe flops from one position to the other to change from inside air recirculating to outside air or from floor heat to defroster?
Click this picture to get a better view!


But I think that will have a spring to keep it one direction until there is vacuum puts on to move it. So if you grab that part sticking out the top, it probably moves up and down even without taking the vacuum line off.
If you have a helper to change the hear and air settings inside, you might see this thing move. Or if you have the heat or air inside running and somebody to tell you what it changes, you might grab it and open and close it and let them tell you what the air does inside.
Like moving the damper on a wood stove pipe, if that's one you've been around?

One of the bad things about these rubber vacuum lines is that they get brittle and have leaks that are hard to find. Sometimes it is easy to spot because the fall apart when you touch them but other times it is a slit along a bottom side where it's a trick to find them!
When they get brittle, some just go through and change all they can see!

But that brings up a question of what they call things! I think of engine driven as things like the blade on a lawn mower. But they might call it engine driven if it had to have the engine running to make the vacuum to move them??

Some place there has to be a hundred people dreaming up ways to confuse us!!

[Bones2003]

Here is a link to a good website with specific information on the vacuum operated AC/heat/defrost units in Winnebago RVs. There are several troubleshooting guides as well as vacuum hose routing/function information.

https://www.comfortairgr.com/rv-hvac-downloads/

[7997redtail]

Wow that’s a lot of info. I started looking at some of the relevant links then realized I needed to know which brand is installed in my unit.

I did some research but can’t find if it’s an Evens, Denso, Victory Etc. anyone know where to find that info? When it stops raining I’ll go look at the actual unit for markings

Thanks

[7997redtail]

I checked and my ac has SCS in Fort Worth Texas on a label. I was just going back to the site link that worked yesterday but doesn’t today. Humm. Only active on weekdays?

Reasearch says they are bankrupt.

[Morich]

Your weekend didn't start early by chance??
It's still a weekday around me!
You might want to try the links again. I keep finding them here and there as not working and work 10 minutes later.

I think we are getting too much stir and not enough wisdom in the internet world!

[7997redtail]

I just got in from testing a few things. Note to me vacuum doors don’t work until you start the engine

I tested first without the engine running so I could hear any valves. Waste of time,

Once the engine was running switching between defrost, feet etc all work fine.
Switching between AC and AC Max open and closes the recirc door. It moves freely and looks to be working well.
Outside I felt the hose going into the top drivers side and both sides of the valve located on the drivers side. Top hose and both sides of the valve were warm (same temp) with or without AC or AC Max on.

Next step is to check that vacuum line and the valve. Not to sure how I’m going to test the valve other than to have someone switch it while I hold on to feel any motion. If I have to pull the valve I’ll wait until I either change the antifreeze or some other cooling situation arises.

I just thought of a question. Anyone know how much vacuum is used on this system?

Thanks

[Morich]

Sounds like you are getting into some information of sorts.
I've never tested the vacuum for how much, just if it sucked my finger on the end. Pretty lame meter but worked at the times needed!
Lame thinking would say it can't be much if they use rubber tubing and it doesn't flatten the tube?
I keep coming back to wonder about a valve in the radiator hoses about an inch or so thick that take hot water from the engine to the heater core. If the air flaps that change where the air goes seem to be working but the normal AC setting seems too warm, maybe it is the valve that should shut off hot water to the core is not closing?

Is there enough open space to spot what I call normal radiator small hoses?
Maybe look for a bulge along them that might be the valve?

[Bones2003]

Morich is correct (as usual) that it doesn't take much vacuum. A handy tool for this is a a handheld vacuum pump like is used for bleeding brakes. One thing to keep in mind, once the valve is open and hot antifreeze goes through it, the hose will get hot/warm and stay warm for quite awhile even after the valve is closed.

Here's how I would check the water valve:
EDIT: Start with a cold engine.
1) Turn the A/C off, the air control to dash vent, fan to medium, and the temperature control to cold (blue zone).
2) Start the engine and let it warm up. If warm/hot air blows out the vents then the valve is likely stuck open or there is a problem with the valve vacuum control line.
3) If the air out of the vents is not warm/hot, set the temperature control to hot (red zone).
4) If the vent air gets hot, the valve is probably working okay. Then set the temp control back to cool (blue zone) and see if the air temperature out of the vents starts to cool off after several minutes. It may take a bit to push out all the heat from the system. If the air does eventually cool off, it is another sign that the valve is working okay.

[7997redtail]

I’ll give this a try tomorrow.

Thanks

[7997redtail]

"the hose will get hot/warm and stay warm for quite awhile even after the valve is closed."

Interesting point. Ill try your troubleshooting technique later today.

Thanks

[7997redtail]

"Is there enough open space to spot what I call normal radiator small hoses?"

In the second picture of the original post it shows what I expect is the valve you are referring to. Very difficult to get two hands into.

I just thought of two questions.

Does anyone know how the green tube disconnects from the valve? Id hate to pull wrong and break it.

Can someone confirm what the green tube represents? I think the AC guys use colours like electricians do.

Thanks

[Morich]

I'm not sure what we are seeing in the second picture, so may be confused?

In this picture is the top hose about the size we can just wrap our hand around or is it the way big that is more like 2-3 inches thick? Pictures can look different from different distances but I was thinking the upper is the "normal smaller size radiator hose that feed the heater and then the even smaller second hose with the valve might be more like 1/2 inch thick???
That second one with the smaller looking size and valve, I might guess was some sort of emissions control line and the green is a wire for controlling it.
so some confusion to clear up on what I am seeing!
Click this snip for better view of what I'm thinking.

[7997redtail]

The hose is about one inch and the one I tested and found warm. The green is tubing. Pretty sure this is the circulation valve.

[Bones2003]

Yes that does look like the circulation valve with the green tube. Keep in mind that the circulation valve may be an electric valve not necessarily vacuum operated. On the F-53 engine I thought the circulation valve was easily accessible near the top front passenger side of the engine if you remove the doghouse cover (refer to the figure in your post #5 above).

[7997redtail]

Impeccable timing. I just came in to tell about the latest testing.

As per “bones” I ran his tests and it appears that the valve is working fine. I get warm or cold air when I’m supposed to.

So that begs the question I started with. Why would I get warm air in AC mode and nice cold air in AC Max mode?