Dash AC

Topic: Dash AC (Read 709 times) previous topic - next topic

Dash AC

May 14, 2021, 04:51:35 pm

I think the AC dash is a joke.
However.....it had been working for us
Until today
The air blew out my widow defrost vents, but I could not get the air to come out of the normal, dash vents. When I turned the " mode" dial, it still just blew out of the windshield vents.....
Until it, MAGICALLY, changed to the dash vents. The fan spurred adjuster didn't respond correctly, either.
I was going to open up the dash to see if a cable was loose, or something connected to a baffle, but realized I have no idea of how this thing works.
Anyone familiar with this joke of a system?

Re: Dash AC

Reply #1 – May 14, 2021, 05:35:45 pm

Some of the registers are vacuum controlled and some have electric actuators. I have the vacuum type someone with your year and model might tell you what you have.

Re: Dash AC

Reply #2 – May 14, 2021, 05:47:10 pm

A vacuum leak defaults to defrosters. So. You probably have a vacuum leak somewhere. Or, it could be the vacuum pump itself.

Re: Dash AC

Reply #3 – May 14, 2021, 07:20:01 pm

Glenn, the flapper motors are vacuum powered controlled by electric valves. My defrost motors work but the controller quit 10 years ago. No fixing the electronics so a work around wiring patch to a switch closes all else and opens the defrost flappers. All of this is 20 years old meat and potatoes technology.

It would be nice if it was all solid state and computer controlled from a giant touchscreen panel somewhere on the dash or better a holographic see through hand gesture enabled total coach control system that shows up anywhere you want it. Maybe just a neural interface, be careful of what you think.

Re: Dash AC

Reply #4 – May 14, 2021, 09:14:22 pm

Quote from: Twig – May 14, 2021, 05:47:10 pm

A vacuum leak defaults to defrosters. So. You probably have a vacuum leak somewhere. Or, it could be the vacuum pump itself.

How do I trace a vacuum leak???
Where is the vacuum pump located???
is it repairable??
A" work around wiring patch....'

? what the heck is that? How do I do that?
Or do I just " live with it"?
Pretty dangerous when the windshield fogs up....oh, it defaults to those vents. Great.

Re: Dash AC

Reply #5 – May 14, 2021, 09:40:14 pm

The vacuum pump is under the stairs. When the step is down it can be accessed. I had a vacuum leak there.

Re: Dash AC

Reply #6 – May 14, 2021, 10:00:39 pm

Glenn,

Vacuum leaks suck.

Vacuum pump is underneath the front steps, or in front of or towrds thw inside. Mine was replaced when they did the override, and then we changed to an electric step so now ours in forward of the step. If it doesn't work then replace it. Amazon.com: Benefast 904-214 Electric Vacuum Pump Compatible with for-d...

I have two 12v fans mounted on movable bases that plug into the 12v outlets. Even with the defroster blowing sometimes we need more, especially on the pass side when the fog obscures the mirror. Something like these... Amazon.com: Prime Products 06-0850 Heavy-Duty Chrome Fan: Automotive
Lots of choices, works for a breeze on the driver or passenger s well.

I didn't do the override switch, it was at FT in 2011 last time I was there for service. I have no wiring diagrams for the heater controls. I can look and see if I can figure out what they did.

Not always easy but the process is the same. Identify the problem, try to understand how it works so you can start to figure out how to fix it, ask questions. The more you can learn the better you will be able to figure these things out.

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Dash AC

Reply #7 – May 14, 2021, 10:31:51 pm

I just recently replaced both the vacuum pump and the reservoir with a dorman vacuum pump from Amazon. Sorry I'm too tired right now to look up the link but there is threads on it here on the forums. Of course putting a new vacuum pump in with a vacuum leak we'll just burn out the pump. I just needed a new pump cuz it was totally rusted out. It sounds like that's your problem. It's located under the step as others have mentioned. It's a black square box with a vacuum line going to it and a 12 volt power wires.
As far as the dash air is concerned I agree that it's an issue. I was going to try to work it myself but I don't think I have the expertise to do it so at some point I'm going to have to go to somebody and see but I suspect that I'm going to have to replace most of the parts I don't really know when the last time the dash AC was working on my coach.

Re: Dash AC

Reply #8 – May 14, 2021, 10:33:32 pm

On mine it is easier to prop the heater box doors to direct everything to the dash than chasing leaks. That's what I did. But. I don't live in Maine. Defrosting is not required in NM. Although, if needed, I could un-prop.

Re: Dash AC

Reply #9 – May 14, 2021, 10:42:38 pm

Here is the vacuum generator under the step and a pic of the electric pump I replaced it with. The pic is another members example and I built one just like it.. got the parts off Amazon

Re: Dash AC

Reply #10 – May 14, 2021, 11:08:05 pm

I had trouble at first defrosting the pass side as the vent wouldn't work properly. It was like I had two left hand vents. I took the vent
apart and changed the louvers so they would face more to the left and it works great now. As Roger said fans are great but I
haven't found a place to mount them. I like the fans in the summer as I turn them so they face us and it really helps with cooling
us.

Re: Dash AC

Reply #11 – May 15, 2021, 06:37:59 am

Glenn,

A few years ago, I was able to find the switches that are on the dash from FOT.

If yours is like mine (and I suspect it is) then the actual control board is mounted in the center of your dash behind the lower storage compartment. That's where the vacuum control valves are located. You'll find all the various vacuum lines there. Not very easy to access but it can be done.

I have replaced my vacuum pump (my picture above in huff's post) and also a vacuum motor to control the flow of air to the various dash vents. (available from FOT).

If you open things up and do a little sleuthing, it is possible to swap vacuum lines around to help troubleshoot/diagnose what component is not working. The vacuum motor I replaced controlled the passenger side air flow swap from top to bottom vents.

Ed Wittleder did some repair work on his last year and the company that makes it is still in business. He was able to source some parts from them.

Rich

Re: Dash AC

Reply #12 – May 15, 2021, 09:44:37 am

Thanks, to all
Great response
When we fog up, it's usually in a big rainstorm, with inside/outside air temps different
I will install fans, like Roger has.
When it fogs up, it isn't a pleasant experience.
I was confused about the vacuum pump, as our steps and step cover work fine.
I'll grab a bottle of soap water and take a " look see"

Re: Dash AC

Reply #13 – May 15, 2021, 09:57:07 am

Glenn the vacuum pump has nothing to do with the step and stair cover operation, it is just located in that area. Lift up the vinyl flap covering the hold at the fold down step, it might be back in there otherwise look outside in front of the step box or towards the middle of coach behind it.

My fans are mounted to a wooden base with a piece of steel glued in place in a recess in the back so they stay in place. The power cord needs to be 16 ga or so wire. Too small and there is too much voltage loss and the fans will run slower.

Re: Dash AC

Reply #14 – May 15, 2021, 11:08:08 am

Glenn. For a second there it sounded like "Whining on the YACHT ".

Just got ours working after 10 years or maybe longer. Didn't work when we bought it. I'm lovin it but the ducting is still a little sketchy.

Re: Dash AC

Reply #15 – May 15, 2021, 11:09:30 am

Glen I also found that the vent needs to be push down in the front maybe 20 degrees and the side vents about 45 degrees
and that should keep the window clear. I have not any trouble since I have done that and have driven in all kind of horrible
weather. I definitely think dash fans are great and would install them if I could figger a place to put them. In my Monaco
they were in the middle of the dash where the defroster vents are in the Foretravel.

Re: Dash AC

Reply #16 – May 15, 2021, 01:21:46 pm

Quote from: GleamB – May 15, 2021, 09:44:37 am

I'll grab a bottle of soap water and take a " look see"

Glenn,

As Roger says, the vacuum system sucks. Therefore, soapy water will not help. You just have to listen for the sucking sound of the air leaking into the hoses via a rotted hose or a loose connection.

Richard

Re: Dash AC

Reply #17 – May 15, 2021, 01:47:03 pm

[quote author=Bob & Sue l

Just got ours working after 10 years or maybe longer.

And just what did you do to it to make it work after 10 years?

This may also sound like whining...

Re: Dash AC

Reply #18 – May 15, 2021, 03:46:02 pm

Quote from: Jan & Richard – May 15, 2021, 01:21:46 pm

Glenn,

As Roger says, the vacuum system sucks. Therefore, soapy water will not help. You just have to listen for the sucking sound of the air leaking into the hoses via a rotted hose or a loose connection.

Richard

If the vacuum comes from the engine (not a vacuum pump) you can spray a "tiny bit' of starting fluid in the area of where you suspect the leak is and the engine will rev when the spray hits the leaking hose. NOTE- WORKS ONLY ON GAS ENGINES !

Re: Dash AC

Reply #19 – May 15, 2021, 03:56:27 pm

Quote from: RevRick – May 15, 2021, 03:46:02 pm

If the vacuum comes from the engine (not a vacuum pump) you can spray a "tiny bit' of starting fluid in the area of where you suspect the leak is and the engine will rev when the spray hits the leaking hose. NOTE- WORKS ONLY ON GAS ENGINES !

Yes, I use WD-40, lots less volatile than starting fluid/ether.

And, as you said, not applicable to any diesel-- just gasoline engines, as diesel engines have ZERO VACUUM.

Re: Dash AC

Reply #20 – May 15, 2021, 06:18:57 pm

I think mine is a diesel

Re: Dash AC

Reply #21 – May 15, 2021, 08:43:25 pm

Quote from: GleamB – May 15, 2021, 06:18:57 pm

I think mine is a diesel

Yup, very little question-- the Cummins M11 IS a diesel.

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