Thanks Scott and Rusty,Let the Barth run this morning- the third line (pointed towards firewall)does have air coming out of it when it is running. When you shut down the volume increases, when I tried to block it, it blew off one of the hoses from the bottle. Is this a pressure release of some sort? Scott, thanks for the heads up on MWrench post. Although it is probably a little over my pay grade, it does give me a little better idea of what is going on. Since my cruise doesn't work and the air brakes loose there pressure within an hour of shutting down. I must have some air/vacuum leaks somewhere. From what I read there is another venturi in the engine compartment?

It sounds like you blocked the venturi exhaust; the back pressure will blow the vacuum line off in that case. The venturi has to have airflow through it to generate vacuum.

The venturi will bleed air from the brake (air) system.

The cruise control also operates on vacuum; a leak in the cruise control would not cause an air leak from the main system.

I spent most of the afternoon trying to figure out why I can't get air out of my dash vents(very little). I replaced the hoses, took out the control unit, checked the back end to see if it was ok..from my untrained eye everything seems alright. Stll almost everything out the defrost..what puzzles me is that the "off" button works, but none of the rest. Also the hose that I was talking about earlier by the firewall (left on the picture) runs down to the brake resevoir and there is air coming out of it. You can hear the airflow for about 10-15 min. after shutdown. Is that what it is supposed to do? As Rusty pointed out that has got to be taking air from somewhere...and the electric pump would be the better answer... but right now I don't know if it is the pump, the controller, or the hose that is losing air . In case anybody needs some part numbers for the controller I posted some pics..... the last number on the black side is "3"

I forgot to mention on the second picture, top side of the controller with the temp lever, there is a two prong plug...nothing was plugged into it... didn't see anything..don't know if that means anything.. Also as my frustration level on the vent problem was reaching its peak I decided to divert my attention for abit to my steps that are not working... took the motor and gear box apart and discovered that moisture had gotten into both and locked up the gearbox and shorted out the motor..well, that at least will be an easier fix... new steps! Thanks,Gerald

Thanks Rusty.. we must have been posting about the same time.. OK now I understand the air flow and why the air brakes lose there pressure so fast.

If you are loosing air thru the vacuum generator, it is defective, or you may have a leak in the vacuum line somewhere and that is causing the vacuum generator to run all the time, There is supposed to be a lock out in the generator that will stop it's operation if the incoming air pressure drops below a certain pressure.

If the dash HVAC isn't working, that may be caused by the lack of vacuum. Most dash controllers require vacuum to operate the various valves and flaps. I think you need to track down the vacuum/air loss problem first.

Yes there should be another vacuum generator near the engine for the cruise control but it is not tied into the front system but a leak here (vacuum or air) would also deplete the main air system with the engine shut down.

Gerald, I have a front venturi that leaks down also. I eventually will replace it with a vacuum pump or such. I may even put a manual shut off in line, then I can turn the venturi off when in camp so I don't have to wait as long to "pump up".
If you do a search on the website you'll see there is alot of questions on the air leaks from the nose of the coach.
on your heater controls. Now I haven't looked behind my dash for a while. But If there are vacuum lines to the controller check and see if vacuum is present at the controller Or you can find the actuator for the blocker doors and see if that has vacuum and work your way back. The actuator is a diaphram type and they have arms that move the doors. They might have more than one I haven't had a problem there yet so i dont know. It is an old dodge van setup. I had the same controller in my 1988 B250 van.
If the coach has been sitting a door seal maybe stuck, or the system needs exercise, it doesn't take a lot of force to overcome the actuator movment. When my coach sits sometimes stuff like this happens and on our shakeout run these bugs work themselves out once we start using them.

Thank you everyone for the help. It is bright and early and I am determined to fix this today!! Now that I have an idea of what the three barbs do.. one bleeder, one vacuum, one return. First the hose that hooks up to a tee has a very small toothpick size line that runs to a harness in the back of the controller. This line was hooked up to what I believe is the return barb, so I switched it around with no difference. I checked for vacuum in the harness and I feel nothing, no matter which barb I hook it to - how much vacuum should there be at harness? Should it be quite noticable? How much suction does this vacuum generator have? Even at the generator point of the barb it doesn't seem to suck very hard. I don't have any gauges to check but I am beginning to think that this vacuum generator is not producing enough vacuum

Update 11:00 am..so far I have found that if there is not enough vacuum to the controller it defaults to the defrost position. I think the controller is fine and have decided to take the advice of putting in an electric pump. Thereby also eliminating the air noise. No Volvo devices available here. Does anyone have suggestions as to what vacuum pump would be a good replacement? Also do I then simply turn in a plug where the old vacuum generator was? Thanks again... Gerald

4:30 pm....found a Volvo vacuum pump on Ebay $39. Also ran into a gentleman who has a controller out of a 92 Dodge van.. said he would take a couple of Heinekens for it.. sold!

IIRC, the default is outside air (the flapper valve on the right below the dash; it should close the grill to cabin air - vertical position).

My controller doesn't have a 2-prong plug, but the male spade connector on the lower right is 12VDC in, the one on the left is power to the A/C compressor clutch. With the controller in A/C or defrost, there should be continuity across those terminals.