Rear vac line on AC Boost Solenoid?

[RamThis]

What does this vac line control? I checked the vacuum line toward the front of the AC boost solenoid, and it gets good vacuum when I turn on the AC, and the AC boost works perfectly. But, the rear line does not seem to have any vacuum on it at all. Someone said it was to boost idle when in gear, but, I checked vacuum on that line in P,R,N,and D and there is no Vacuum on it in any of those settings. What gives?

[HondaBoy]

i think its connected to a thermal valve to bleed the vacuum. not quite sure, but i think that's why that one doesnt show much if any vacuum pull.

[A20A1]

check it when the motor is cold and when it is warm... also it may be cruise control related... I'm not sure.

Try other things like tuning on the headlights...

what vacuum line # is it by they way? 30? I might be able to track it's function if I know what solenoid it hooks up to.

[AccordOwner]

On Accords with a/c and auto. trans., the idle boost controller has a double diaphragm, one for the a/c, on the rear, and one for a cold engine or when the car is in gear. The a/c solenoid is on the driver's side sidewall, and the other is in the blackbox on the passengers side. If you mean the hose toward the front of the car gets vacuum from the a/c, your hoses are crossed. The a/c one is #30and the other from the box is #21. If you have no vacuum from #21 when in gear,(or cold engine) the idle boost solenoid is probably bad. Pop the cover from the box and follow #21 to find the solenoid. It is probably bad, or not getting voltage.

[RamThis]

EXCELLENT. I will check that out. Thanks AccordOwner.
BTW, With this setup, can I set the Idle speed when OUT OF GEAR to about 800, and have this diaphragm booster keep the RPM up to about 800 or so when I put the car in gear? I swapped out the vac lines because for some reason when I turned on the A/C, the idle kept dropping. I thought I had the lines crossed originally because when I swapped the lines, the A/C boost started working.
Ive always found it odd that a car would have to idle so high in N or P to keep the idle good when you put it in gear. Guess this answers why.
Now, if I find the solenoid in the black box is not getting power, where do I look to find where the power is supposed to be coming from? The shift quadrant in the center console? Im hoping its just a bad vac line or something.....
OK, vac line 21 hooks to the front connector on the boost solenoid body, which looks to come from the black box, through the hardlines around the back of the carb, and down directly to the solenoid. Line 30 looks to come from that solenoid on the driver side fender. The solenoid always has vacuum coming to it, and only opens when the AC is on. Is this right? This is how I read it from my underhood routing diagram.......


Here is how I originally had it hooked up (http://www.dodgetrucks.org/gallery/data/500/100_2253.JPG), now the lines are swapped so I could make the AC boost park work right. It didnt seem to work when I had it hooked to the rear connection where its supposed to go, even when I screwd back on that screw facing toward the firewall.

Here is the solenoid (http://www.dodgetrucks.org/gallery/data/500/100_2254.JPG) that connects to the boost solenoid, the pictured solenoid is on my driver side fender. When I turn on the AC, it gets power, and vacuum flows through it.

This is the vac diagram (http://www.dodgetrucks.org/gallery/data/500/100_0345.JPG) under my hood.

[RamThis]

Ok, I went out and checked, no vac on 21 to the boost solenoid. So, I went direclty from the black box and checked 21, no vacuum. Opened up the black box and found which solenoid 21 connects to. The solenoid in the black box has no power to it in park, but shows power in gear, which is how I assume it is supposed to work. I followed the second vac line that connects to the solenoid, it is line 2. It comes off the hard lines, and it has full vacuum. So, I assume the solenoid itself is bad????

One STUPID thing I realized after I put it all back together was that line 2 comes in, and has a T in it before it connects to the solenoid, that leads to some big blueish green plastic doohickey. I SHOULD have unhooked that and capped off the T and checked for vacuum through the solenoid at that point I would guess, or does this matter?

This shows line 2 leading into (http://www.dodgetrucks.org/gallery/data/500/100_2506.JPG)the black box, and, what I just noticed in this pic, leads to the blue thing, and another solenoid that I didnt notice in my quick inspection, the black one with two screws holding it. What do these two other parts do that 2 is connected to?

This shows the solenoid (http://www.dodgetrucks.org/gallery/data/500/100_2499.JPG) from the firewall side. Its the black and orange box with the red and black wires connected to it. These wires have power to them when in gear, and are dead when in P. Also on a side note, the silver solenoid next to it with the black top, was kinda hot to the touch. Is this normal?

Finally, this pic shows the solenoid (http://www.dodgetrucks.org/gallery/data/500/100_2497.JPG) from the top, with the little filter connected to it. Its the one on the right in the pic, but, as it sets in the car, its the one on the driver side rear of the black box.

Hope the pics are helping some...... :bow:

[A20A1]

Vacuum is supplied via #2, if #2 connects to the solenoid you check the other port on the solenoid to see if vacuum from #2 reaches the other port.

http://www.3geez.com/showthread.php?t=45880

looks like I labled some things wrong... I was using the manual, but it seems like they didn't use the same numbers or were missing a few.

I might has put line #8 in place of line #21 if thats where you say it goes. The solenoids look simmilar enough.

however that particular diagram didn't include the second port on the A/C idle boost diaphragm so it didn't have #21 to begin with.

:(


I don't think the green ones bleed vacuum

the ones with the small filters on them do though.

[A20A1]

I might need you help to clear the vacuum line routing mess up... it's easy to get your wires crossed looking at the pic... so please be careful but I'm sure I have some wrong... I see the gap in the image where #21 would have been.
I see #21 on your diagram.

[RamThis]

Maybe these will help..... I cut these out of the PDF pics of the accord shop manuals posted here by someone. These help make some more sense of things for me, at least, what they are called LOL. Still dont know what half of that crap in the black box does!!!! :bowrofl:

http://www.dodgetrucks.org/gallery/data/500/Honda_Black_Box.JPG

http://www.dodgetrucks.org/gallery/data/500/Honda_Vacuum_Diagram.JPG

[A20A1]

nice
I added your sticker to
http://www.3geez.com/showthread.php?t=40679

[RamThis]

nice
I added your sticker to
http://www.3geez.com/showthread.php?t=40679


Cool, how did you get it so nice and clear and in B/W like that? Shame that bit of glare on the top corner kinda faded out some of the letters. If you want I will retake that photo and try to get rid of the glare.....:rockon:

[A20A1]

Thats okay... I edited the image and labled the vacuum lines in the black box thread... let me know if #24 & #27 are really intake manifold vacuum or not... I'm pretty sure they are.

[RamThis]

Thats okay... I edited the image and labled the vacuum lines in the black box thread... let me know if #24 & #27 are really intake manifold vacuum or not... I'm pretty sure they are.


27 shows to connect to the back of the carb somewhere in the diagram I posted.

24 looks to hook up to the same pipe on the tree, further over to the passenger side, on a nipple facing downward.

24 and 27 both look to draw manifold vacuum as well.

[AccordOwner]

Sounds to me like your rear diaphragm on the idle boost controller is bad,(leaky) along with your idle boost solenoid in the black box. The diaphragms get old and leak after a while. I take my vacuum pump to the local Pick N Pull and find a working one to use. Majestic Honda sells the controller for about $20, I believe. It is a little difficult to change, so a new one is probably a good idea. Good luck.

[RamThis]

I dont do the wrecking yard thing, Im a new parts guy. I hate replacing a broken part with a part thats about to break, all in the name of saving a few bucks. I would rather spend the extra money and do it right.

I will check the diaphragm with my vacuum pump and see if its holding vacuum. Hopefully it does and I just need a new solenoid and I can get it working right.


Oh, had a spark plug wire pop off today LOL. Wife was driving home and about a block from the house she said it started shaking hard. I popped the hood and instantly saw the problem. The little screw top on the spark plug somehow came loose, and the wire just popped off. So I fished the screw top out of the boot, put it back on, tightly this time, put the wire on, and all is good again. This also told me why I was getting some intermittent rough idling, looks like its been in the process of unscrewing itself and getting ready to fall off for a while, as the threads showed evidence of arcing. Now it idles alot smoother, almost too smooth lol.

[A20A1]

I always hated those wires with removable ends.

The diaphragm is replaceable if you buy the rebuild kit.

I put some teflon tape on the screw at the back to keep it in place better.

[RamThis]

well, I hooked up my vac pump and the front port holds vacuum and actuates the lever like its supposed to. The rear port would not hold vacuum for some reason, nor would it actuate the lever. I kept unscrewing the adjuster in the back until it came completely out. I put my finger over the hole and pumped the vac pump again, and it held vacuum, but, still didnt move the lever. Could something be stuck inside? Seems its bleeding off vacuum around the threads of the adjuster screw. Is there some sort of seal or o-ring thats supposed to be in there? I may order a rebuild kit for it along with the new solenoid tomorrow and when I get it, I will pull the unit off the car and install the rebuild kit and gets some pics and such.

[A20A1]

Like I said, use teflon tape, it will help seal the threads. Also the diaphragm may not be put together right internally keeping it from moving.

also the A/C idle boost arm doesn't move as much as the arm on the idle diaphragm on the passenger side of the carb.

[RamThis]

you know, I wonder if when I unscrewed that screw back when I was jacking with it before I ever got it running, if there was an O-ring in there that I pushed up into the body of it some. I remember it being hard to get the screw back in again that time and just kinda not really thinking much about it at the time. But, I remember doing that and could be why its not moving when I give it vacuum.

It appears that it should move the arm twice, once when you turn on the AC from the rear port, then move the arm a bit more when you put the car in gear from the front port, or they can work independantly.

I think I'll still get a rebuild kit for it, as long as I have to take it off to look at it anyways. Cheap insurance. :)

[Hondaisok]

This is kind of long. I have a disassembled controller right in front of me. The a/c knurled knob has no o-ring, just a spring, I assume to keep it from vibrating out. The knob and the post it is on is covered with a rubber cap to keep it from leaking.(teflon tape would work, also) Now then-the front diaphragm is connected directly to the rod that runs to the carb. It's idle speed is adjusted by the screw on the gizmo the rod attaches to. It resides in the front vacuum chamber. The rear chamber(a/c) diaphragm is a plate with an about 1/4 inch rod that runs from the rear chamber to the front, or in gear idle chamber, which, by contact with the front diaphragm and/or rod, controls how far the rod can move WITHIN THE CONTROLLER. In other words, if you're idling in gear with the a/c off, the front chamber jacks up the idle according to how the screw on the end is adjusted. If you are idling with it in gear and a/c on, the rear diapragm can control slightly how far in or out the rod travels. If in park with a/c on, the rear diaphragm boosts the idle a little more, but the front should have vacuum, also. The rear chamber can't control the arm enough to move the rod. Clear as mud, huh?

[RamThis]

I understand exactly how it works now that Ive followed the vac lines and such back into the black box, just havent seen the internal workings yet. I will eventually replace the solenoid for in gear vacuum and do a quick rebuild on the boost controller to make sure its up to par. Then adjust it and it should be good as new. At least, thats the plan..... :bowrofl: