Mystery low pressure air line

[my38special]

While fixing-up some old wiring under the dash, of my classic 83 Newell, I managed to shock myself on the back of some gauge and this made me jerk my hand away. During this instinctive reaction, I managed to pull off a vacuum-looking line from somewhere. Despite 2 hours of effort, I cannot figure out where the line connects. In accordance with the attached photo, it starts on top of some solenoid-looking-thing near my brake pedal. I've marked the mystery line with a "?" to help show my problem. I note that while the engine is running, it blows for about about 8 seconds and then goes quiet for a longer period (approx 30 secs). This cycle keeps repeating itself. The other two lines that attach to the same solenoid go to a black Dole vacuum canister, but for the life of me, I can't figure out this other hose. I would be extremely grateful to anyone out there with a classic Newell, or one of you other gurus, who knows where I hook up this line.

[encantotom]

my 1990 had a high pressure air powered vacuum pump in front of the drivers side headlight. it used air pressure to move a diaphram that made vacuum and the low pressure vacuum line ran up through the floor to under the dash to a black ball tank that was the vacuum pressure tank for the vent and defroster controls in the plenum. there is a by product of air that blows off of the vacuum pump.

mine sprung a leak and i replaced the whole thing with a 12v pump off of a f350 diesel pickup truck.

from looking at the picture i suspect that is what it is.

the reason for cycling would probably be the vacuum pump is detecting it needs vacuum so it turns the pump on...

i am reaching but it kinda works as an explaination.

tom

[tuga]

Do your windshield wipers work?

My 1987 Newell had air wipers.

Email the picture to someone in the service department at Newell, I'll bet they know!

[jmacstack]

Is your dash air, A/C on? If so, turn it off and see if it continues to cycle. I have a solenoid that blows when the dash air is on and after talking with Newell, it's suppose to be that way. When I turn off the dash air it quits. Good luck, Jennifer

[my38special]

Thanks for the thoughts on my mystery vacuum/pressure lines. Given that some lines go to the dash temp controls, I reasoned that it might be some kind of a vacuum generator. Thanks for backing up this line of thought. Seems like an odd way to make vacuum, but, whatever. I did try the vacuum (pressure?) driven wipers and was surprised to see that they still work. As for the dash air conditioning, it has never worked and so I can't really trial this suggestion. Unfortunately, I still don't know where to hook up the third line. Given the 18" length of this tube, which defines the radius of options, one would think it not hard to find where to hook up the tube. Yet, despite my efforts and even efforts from other family members, none of us can figure out where to hook up this last line. I remain open to suggestions by any other classic owners, who may have the same set-up in their RV.

[encantotom]

on mine there are 3 vacuum lines going to the dash heater air conditioner controls. one is black, one is blue and one is red. the blue and red run from the contol to the plenum in the right front bay in front of the passenger tire where the blower for the genny is. the black one will be a short line that is the source for the vacuum controls on the dash panel and will run from it to the vacuum tank which is a black plastic ball about 6-8 inches in diameter. it is buried in the center of my dash behind the center console. then there will be a larger vacuum line that goes from that ball tank to the vacuum pump. it will be a regular vacuum rubber hose like in cars. the other 3 attached to the controls are much smaller.

tom