Looking for the location of the low pressure port on an 86 motor home Rv , e 350 van front end, 351W engine. Any help would be appreciated. If you have a similar van I would also like a pic of your air cleaner and air intake tubing. Mine seems to be weird, extra inlet on cleaner wit a vacuum driven shut off door. Closed with high vacuum and open with low vacuum.
Thanks in advance for any info.

 

Hi 86 forde350, welcome to the forums !

below will be a typical drawing on an air cleaner system used around that year..
“ extra inlet on cleaner wit a vacuum driven shut off door”
In the drawing the part you are talking about is a vacuum motor. It opens and closes the damper I guess it is called, or door.. When the damper is opened, it allows fresh outside “cold air" to enter the breather through the fresh air pick-up tube.

When it is cold outside and the engine is cold, the damper is closed and air is drawn in trough the heat riser tube that connects to the shroud that goes around the exhaust manifold. This helps put warmer air into the carburetor while everything is cold.

Under the breather on the diagram, you will see an arrow pointing to the “Cold Weather Modulator”. Just to the left of that you will see another arrow pointing to a “Bi Metal Sensor” that can be seen in the cut-away inside the breather.. Most, but not all systems will have the “Cold Weather Modulator”

System without a “Cold Weather Modulator”
The Bimetal Sensor (also called Air Cleaner Temperature Control) needs a constant vacuum source. The other vacuum line will go directly to the vacuum motor.. When the temperature inside the breather is below 75F, the sensor will allow vacuum to close the damper to fresh (cold) air. Different systems have different colored Air Cleaner Temperature Controls and they operate at different temperatures. If you replace it, be sure and buy the same color.. The different color determines what temperature the sensor allow the damper to open. They all should close the damper when the temperature is below 75F.
Brown opens at 75f
Pink, Black, or clear, 90F
Blue, Yellow, or Green, 105F

The Cold Weather Modulator is used on some models to help control air inlet temperature. It traps vacuum in the system so that the damper will not close during acceleration when the vacuum pressure drops. The “CWM” only works when the outside temperature is cold.
If you have a CWM, there are different colored ones, each color operates at different temperatures. It is important to replace it with the same color as that is what was designed for your system..

If you have a CWM then the vacuum routing would be... Constant vacuum source to the Bimetal Sensor also known as Air Cleaner Temperature Control, maybe ACTC.. From there a vacuum line to the CWM, and from there a vacuum line to the vacuum motor..

My guess would be that you have a CWM and it is bad. Or you have a bad vacuum hose.. Or the vacuum motor could also have a bad diaphragm.

A hand held vacuum pump will help you diagnose the problem if the problem isn’t easily found.
I hope this helps..

<a href="http://s472.photobucket.com/user/Annaleigh_123/media/aircleaner2.jpg.html" target="_blank"><img src="http://i472.photobucket.com/albums/rr88/Annaleigh_123/aircleaner2.jpg" border="0" alt=" photo aircleaner2.jpg"/></a>

 

Are you talking about vacuum port or AC suction line port?
DUH! I just looked at the title of your thread.. 86 e350 air conditioning. I am not sure I can help you out here but I am replacing the ac system on my 88 e150..
Does your compressor look like this?
http://www.rockauto.com/en/moreinfo....116807&jsn=441

The high side off of the compressor should be the smaller line that runs to the condenser and connect on the left side if you were sitting in the front seat..
On mine the low/suction side is the larger hose and runs back towards the firewall. It connects to a second hose that is fastened up under the firewall and looks allot like this. In fact this might be your hose.. But if you look at that hose, you should find the low side port.. up under the firewall on the tube.. towards the right side near the evaporator. One end of that hose connects to the evaporator and the other to the line coming off the compressor..
http://www.oehq.com/partpix/motjpg/yf1290.jpg

 

Thanks for your reply. Yes I understand the typical air cleaner set up you posted. Apart from all of that my air cleaner has an extra opening, also controlled by a vacuum motor.

 

Here is a pic of the extra air inlet, on the back of the air cleaner, the line coming out of it is a vacuum line.

 

Well I have no clue now other then another pic I found and it was no help.
http://thumbs.ebaystatic.com/images/...l9p/s-l225.jpg
Its not on ebay anymore either.

Maybe because your RV is heavy, it requires more fresh air intake when you press the accelerator then you would get from the hot air intake until the front damper opens. Where it is located it would draw air from the engine bay which would be warmer then the front cold air intake..

 

Well I found the low pressure port for the air conditioning, it was hidden under the coil bracket of all things. I actually had to remove the coil to access the fitting. Good news is it still has charge. Will need an adapter to convert to r12A cans but thats not a problem. Next I have to trace the wiring for the clutch. Somebody disconnected the purple lead (hot).

 

do you have a York compressor or a FS6 style?
the York looks like this:
http://www.therangerstation.com/tech...mpressor-1.JPG

The FS6 looks like this:
http://www.acpartshouse.com/Content/...l/114993_o.jpg

Apparently your 350 being a RV, the wiring and AC system must be a bit different then the standard E150 or E350..
I have a 1985 E150 and 1988 E150, both conversion vans. I have the ford service manuals for both vans and a EVTM manual for the 88. I also have a Ford complete wiring diagram sheet for the 88 and cold not find a purple wire going to the AC compressor clutch..

On both of my vans the wiring diagram shows power to the function selector switch from the fuse block (power on when ignition switch is on). Then to the Clutch Cycling Pressure Switch, then to the Compressor Clutch.

The 85 diagram shows a GR/W wire from the function selector switch to the clutch cycling pressure switch. From there it is black to the compressor clutch..

The 88 shows LG/P from the function selector switch to the pressure cycling switch then Black with "Yellow stripe from there to the clutch..

You know your clutch cycling pressure switch should be on top of the dryer and you can jump it out to engage the compressor clutch. The compressor will not engage unless there is enough pressure in the system..

I have all new lines, compressor, evaporator, condenser, and dryer sitting in my spare room and hopefully will be replacing my AC system this week.. I am also using R12.
If you wind up needing compressor oil, let me know.. Ford requires a special paraffinic mineral oil YN-9-A for the FS6 compressor and YN-2 for the York compressor. I had to do quit a bit of research to find the correct oil.. The manual for my 88 said to use YN-2 while the tag that came on the new compressor said to use YN-9 which actually turned out to be the YN-9-A. The ford dealers had no clue

 

I have the york compressor. The dryer appears to be more of an accumulator without a pressure switch. The wiring harness from the clutch is two wires, one purple and one green. the green one is connected to chassis ground and the purple one goes nowhere at the moment, it was tucked up in the plastic channel by the wiper housing. The hoses for the ac also run there. This is a replacement engine by a previous owner so I have no idea of the vintage.
Good luck replacing your system. Sounds like you have all the stuff ready to go.

 

I guess you probably have a dealer installed AC system, not a factory installed like mine.
You should have some kind of pressure switch in the system. I'll try to glance at my 85 tomorrow that has a York compressor on it..
This is what my pressure switch looks like
More Information for FOUR SEASONS 35960

I am not that familial with the York compressor but from what I have read they are much better compressors then today's compressors.. I will have to learn when I get back to working on my 85..

here is an article about checking the compressor oil in the york compressor
York Compressor Oil [Archive] - Classic Cougar Forums
I learned a bit reading it..

If you wind up needing some of the YN-2 oil, I found mine at a ford dealer in north GA. and could look up their name and number for you.