Dash A/C temp cool on cold and fine on MAX AC. Bypass valve?

[7997redtail]

That title may be a little cryptic for what i am looking for. I've just been searching and found the information on switching improperly installed hoses, adding a ball valve to shut off the hot water through the heater core and a few others. But i think there is something better and wanted to post the question.

First, i don't want to install a ball valve and need to go out and switch it as the weather changes. I live in BC Canada and you can, like last week, have 70-75 degrees and Kamloops and 2" of snow on the drive back to vancouver. We joke here that you can ski the local mountains in Vancouver in the morning, golf in the afternoon and rest on the sailboat in the evening. Anyways, I'm off topic. I don't want to go the ball valve route.

What i haves seen and hope someone has pictures/information of doing, is adding in a vacuum controlled valve to redirect the hot water hose going into the heater core to the other side of the core. The valve has two inlets, two outlets and a vacuum connection. I watched one being installed in Ford truck the other day and that got me looking. So far I have not seen any info on an F53 installation for a 2008ish RV.

If anyone's done this Id be interested in how and what you used. Where the hoses are (can I access through the front? Or, only through the dog house etc. My RV is a 2008 Sight seer with the F53 engine.

Below is a picture of a valve similar to the one being installed the other day. It seemed to be aiming the hoses the correct direction to make it a simple cut and replace. The second image to show an example of water flow to accomplish the same thing.

Thanks in advance.

 

[Morich]

The way I remember those older heaters, there is a valve that should shut off the flow.
But you mention hoses not installed correctly? Can you tell us more about these hoses and why not just install them correctly?
Is there no valve to close as you move the controls from heat to air?
I'm always a bit skeptical when I read online about things that are not designed correctly as I often find those folks are just missing the truth!

Can you give us some pictures of what you actually have to control the hot water as there seems to be a lot of info that is missing!
When I've had trouble on vacuum, I often find there are too many leaks in old hoses and the valves are okay, just not getting enough vacuum to work under load!
Hard to tell from the drawings if it is an inside or outside access. It may be both to get down to it!

 

[7997redtail]

Good morning. I'm waiting on a DR appointment so may do this in two parts. Morich, the comments I made about hoses incorrectly installed was just reference to my research. I think that was a problem with newer units than mine.

I'm not sure about your comment about not being design correctly unless it has to do with running a constant hit water supply through an AC unit while trying to create child air.

When I get home I'll open it up and take some pictures. I probably should have done this before posting but figured this was something other had already done.

Gotta go I'll come back after looking at my RV

 

[Morich]

What I was getting at is from memory and prone to not being what you now have but it seems to show the valve as being more like a cutoff that is operated by engine vacuum.
What I know about those vacuum lines is that they tend to get brittle and start to leak in sneaky ways.
Sometimes those sneaky things that operate and then may fail at different times, can lead to people getting the idea that the valve is far more complex or that things were not designed right from the start!
Just wanted to mention you may need to look at what you have to see that what you may have read is actually correct!
Sometimes we get info from reports on the internet and need to check where that info came from and if it is actually what we see when we get there!
the way I remember this valve is certainly a thing to check but I think of it as being a pretty simple thing to close off the hot water flowing into the small heat exchanger in the heater.
What I have seen is the valve may not close to cut off the hot water and that leaves us trying to cool hot air! But before jumping to change the valve, I recommend looking at the tubing that controls the valve. If you fold it and see cracks in the tubing, it may be better to just go with changing the tubing, rather than the far bigger job of changing the valve.
I had a brother who was the mechanical guy and he had to come over and show me what I was missing!
When setting at idle, the valve worked and we got cool. But when the engine was working hard and it moved things around a bit, the tubing opened a crack in the side where it was hidden and the valve stopped working!
We could get cool when setting but lost it when driving and that was the normal time when we wanted the auto air to work!
Just recommending care before deciding the valve is a fault as the tubes are a common problem as they get older and it may not be a tube on that specific valve if it uses a common source of vacuum. It can be a tube that is several feet away but lets the whole thing lose the vacuum power to do it's job.

Good luck on the chase. I hope it turns out to be something simple that stays the same and not some silly little thing that changes as you try to catch it!

 

[7997redtail]

Ok I'm back. I just took a couple pictures and I think i can explain this better.

I have two hot water lines going into the heater core box and I have one vacuum line that comes from the temp control to the recirc vent door. If I remember correctly it opens and closes a door by the passenger footwell for recirculated air.

The hot water pipes are labeled #1 in your picture above.

The problem is that i believe that hot water circulates through those pipes all the time. So while you have the AC mode going it has to overcome the heat running through the pipes.

I've seen some solutions where they put a ball valve into one of those lines to stop the flow. The problem is you need to turn that valve off or on depending on then conditions. In Arizona Id expect you to flip it twice a year. Up here its very different. You might want AC and heat multiple times during a trip.

So my original question was looking for info on installing a valve like the one picture above and if anyone had done so, any advice?

The valve is controlled by vacuum. I would suspect you could "T" into the recirc door vacuum line so it redirects the hot water when you call for recirculated air. Like you would do when running your AC.

 

[7997redtail]

BTW, the vacuum hose looks and feels good.

 

[Morich]

You may have different than I've seen but the name on the parts is valve water/ vacuum controlled and that is what I would expect them to call a valve to shut off the water!
I might also expect a valve to close the air flaps but that is a different part that controls the air, not the water flow. Unless you are sure, I would want to check along those water lines for a different valve than you have seen so far.

I can't think of anything else they could mean when they call it a vacuum controlled water valve?

One way that I find to cross check drawings info is to move beyond the 2010 model year or look at RV close to what is in question. In this case, I took a look at the 2010 model adventurer and they give a different picture of this valve.
In this view they show looking down from above and much bigger!
This makes it look like one has to get under the engine cover to find the valve.

I can't imagine with heat and AC being the basic same design for so many years before the 2008, that they would not have built a valve in to cut the hot water flow. Just too obvious that it would be needed? Since this is not a part of the Winnebago build but what is used on tons of trucks of that age group, I would believe it has to be there.
Turning off the heat was never a problem on any of those older trucks I've driven.
Mostly we had trouble getting warm!
Testing the valve can be pretty simple as it moves with vacuum. If you take the tube off and hold a finger on the end, you should feel it suck your finger. Then if vacuum is good, the valve may be stuck, so sucking on the tube will let you see if the valve moves or not. Several things can go wrong on them as they get some wear. One is the rubbery diaphragm inside can split and then the valve won't move.

But that can be the tough part if you can't find it! But all the online info seems to say it should be there on a number of different years of that group!

Sorry but that looks the best I've got!

 

[7997redtail]

I’ve read a lot of your replies to other messages and I’m always intrigued by your thought progress. Same thing here.

I’ll pull the dog house tomorrow. I think I need to see if that valve is there and working. Shouldn’t be to hard.

Having that valve in place could be why I haven't found someone putting in the valve I was asking about.

Thanks I’ll be back tomorrow.

 

[Woofer]

Well, I can take it one step further... Just disconnect your hot water supply going to the heater box completely. Cut both engine HOT WATER lines going to/from the heater box, and add in some SKID-STEER Quick Disconnects under the dog house. I can run all summer and get COLD AIR out on my dash. In the fall or on a cold night, I just pop the lines back together and "WHA-LA"... I got HEAT. (They are leak-proof and rated at 2,500 PSI)

 

[Woofer]

I might add my (2003 34D Workhorse) Dash AC system has been DIY Modified so it actually works like it should have out of the factory

 

[7997redtail]

Well, I can take it one step further... Just disconnect your hot water supply going to the heater box completely. Cut both engine HOT WATER lines going to/from the heater box, and add in some SKID-STEER Quick Disconnects under the dog house. I can run all summer and get COLD AIR out on my dash. In the fall or on a cold night, I just pop the lines back together and "WHA-LA"... I got HEAT. (They are leak-proof and rated at 2,500 PSI)

I bet those connectors are worth a few bucks.

 

[7997redtail]

So i started up the RV with the heating system off. Once it was warmed up i felt the hoses going to the heater core and here is what i found out.

Heater/AC off hoses cold

Max AC hose to valve side warm but cold on the other side of the valve. Therefore its closed on Max AC

Regular AC both hoses hot. Therefore, the valve is open allowing hot air to circulate while calling for AC (no wonder its not very cold air coming out of the vents).

As for the recirculation door by the passenger foot well.
Closed on regular AC (recirculating interior air) and open on Max AC.

Question Why does

 

[7997redtail]

So i started up the RV with the heating system off. Once it was warmed up i felt the hoses going to the heater core and here is what i found out.

Heater/AC off - Both hoses to the core cold

Max AC - Hose to valve side warm but cold on the other side of the valve. Therefore its closed on Max AC

Regular AC - Both hoses hot. Therefore, the valve is open allowing hot air to circulate while calling for AC (No wonder its not very cold air coming out of the vents).

As for the recirculation door by the passenger foot well.
Closed on regular AC (recirculating interior air) and open on Max AC.

Questions
Why isn't the recirc door closed for both AC modes?

When the recirc door closes is it getting a vacuum or is the vacuum being turned off?

When the hot water valve is opened is it getting vacuum or is the vacuum being turned off? (these two questions might help determine if I have a vacuum source for option two below).

Conclusion

Option #1
I can do like a lot of people and put in a ball valve. Easy Peasy and cheap enough. Or go more expensive and put in a "skid steer/ hydraulic" connector. The problem with both these solutions is switching the water flow on and off while driving and going through multipul heat zones in a trip. I guess i could plumb the ball valve to have access from the side of the dog house.

option #2
Buy a vacuum or cable activated recirculation valve like below. I may be able to control it through either the recirc door vacuum or water valve vacuum. Installation would be pretty easy to do from the dog house side.
View attachment 1315737

 

[Morich]

The thought of getting out to open the hood when switching from heat to air is not a good idea around my house! Three o'clock in the morning we need heat when going to work. Three in the afternoon we may need air! My wife might need it changed three times in a hundred miles!
NOT doing that twice a day if fixing the OEM is an option!

So did you find the parts as the drawings for a different RV show or something different?
Getting the good drawing info is not easy when looking only at the Winnebago site as they only deal with the RV side and pretty much skip the chassis work that they leave to the chassis folks.

 

[Morich]

Posting at the same time but it now sounds like the heat/air controls are the problem and they are likely not handling the switch correctly!
Not having full drawings of the chassis side, I have no way to look at how that gets done. Does it use different tubes that some may be leaking vacuum or is it some small point like a tube dropped off the fitting at the control head?
Not enough info there to make a good guess.
I have not dug into the controls in so long it may have totally changed.
They may now use rubber tires instead of round stone!

But the point is that they were closing off the heat in earlier models of all kinds of vehicles, so thinking they just did not design it do that in this much later model is just kind of missing the whole idea!
Over the years , much of our country has lost the mechanical nature that used to just be part of growing up.
Just tooo easy to put out the big bucks to let others do it!

 

[7997redtail]

The drawing you posted was correct. I think my next challenge is to determine the vacuum system. Ill need to find out if I can put the single hose version in and have it close when calling for regular AC.

Good point on checking elsewhere. I learned about this when a friend was installing one on an F350 Diesel. Maybe Ill go peruse their sites.

 

[Woofer]

I bet those connectors are worth a few bucks.

Here are the links... I only disconnect them when traveling in the HOT part of the summer up here in the NE (in July-August). For folks further south, it would add 4-5 degrees of colder air by keeping the hot water out of the box. The vacuum valve only shuts down the hot water flow on input to the box; there is still a hot water presence through the outlet hose.

Hydraulic (quick disconnect) Connectors. (I erred... They are more durable than I thought!)
Features:
Nominal Flow Rate: 12 GPM
Max Flow Rate: 24 GPM
4000 PSI Rating
23,000 PSI Burst Rating (Coupled)

https://www.amazon.com/Hydraulic-Connect-Tractor-Couplers-Pioneer/dp/B08CDCG2NT?pd_rd_w=TYTgj&content-id=amzn1.sym.545f2ac1-7392-463d-83f6-77ac6b95c5ce&pf_rd_p=545f2ac1-7392-463d-83f6-77ac6b95c5ce&pf_rd_r=2BN3F05151EYE5VPH1J1&pd_rd_wg=qRHDI&pd_rd_r=8ad40477-e075-4e4f-97ff-957e5196edc1&pd_rd_i=B08CDCG2NT&ref_=pd_bap_d_grid_rp_0_12_t&th=1

5/8" Hose adapters

Amazon.com

 

[7997redtail]

I’m shocked. That’s not bad at all. Thanks for posting

 

[Woofer]

I am not the person who came up with this little gem. Credit goes to Kevin Caudill and his YouTube Channel.
Go take a look... Kevin Caudill

 

[7997redtail]

Wow. Interesting page he’s got. woofer above pointed this out too.

Thanks for the link. I’m going back to see what else he has