Issue with Fresh Air Controls

[donagain1]

I've scoured through 9 pages of threads dealing with the Fresh Air Blower and it's controls, but saw nothing specific regarding my situation, so here's yet one more thread. On my '85 Cab, the RED knobbed slider on the dash panel is not moving it's associated flapper. Either the cable core is seized to the housing, or the flapper itself is merely jammed. Simple enough to diagnose, I'm thinking... just disconnect the cable at the flapper's crank arm, jiggy the dash lever, and see if the cable moves freely, then try to move the flapper crank to see if it's the flapper butterfly that's bound up. Piece of cake, eh? HA! Seems that's the way to go alright, except for a slight access problem. The heat diverter flapper is pretty well situated behind the master brake booster, and getting my fat hand in there to even touch the thing, let alone loosen the retaining nut(s) results in cramping, bloodletting from gouges, & back spasms from leaning over the fender to reach it in the first place. Arrgh! This is a long preamble to asking what's the best (easiest) way to access that flapper box. Moving the brake booster seems like major PITA to be avoided at all costs, and removing/relocating the blower motor housing, a more manageable PITA seeing as how a ton of people have done so to R&R their blower motor, might be the way to go IF it will expose the heat diverter flapper location adequately? Obviously, I don't want to go through the gyrations if it won't get my hand to where it needs to go. Who's had first hand experience with this? Last night I realized that having hot air actually come out the defroster vents would be a really good thing.

[gazzerr]

Ah yes - this is a pain. It took me a couple of tries to get this right.

Basically you have to adjust things so that the flappers are free and synchronized to move their whole range of movement back and forth otherwise the lever will freeze up. And those bowden clips are a massive pain in the butt. I ruined a bunch of those before I learned how to take them off and put them back on. And don't bend the cable or you are hosed. You don't need to remove the brake booster.

Check out this thread:

911 SC Climate Control Bowden Cables

I removed the front fresh air blower and plenum box and that gave me quite a bit of room. It's not too terrible to pull it part.

[donagain1]

Just read your post, gazzer, thanks for the insight. The telling thing to me is that R&Ring the air plenum is the way to go.

[gazzerr]

No worries. Yep then you can see the cable that runs behind the plenum (heat from memory). If you pull the tops off the housings you can watch the flappers moving back and forth. Getting the spring clips on and off the housing tops is interesting also. They spring around like bullets .

[javadog]

You can loosen or remove the cables without taking everything out, so have somebody work the control while you look at the other end. You should be able to see the problem before you take everything out. The distribution boxes are pretty simple devices.

JR

[donagain1]

Once again, thanks Gazzer! JR, I agree that the distribution boxes are essentially simple. Without anyone to help me out with this to do as you suggested, I had to resort to extremes. I taped my iPhone to a cardboard box, set it to record video, aimed it at the area in question, and worked the lever inside the car myself. I felt stupid, but at least I saw what wasn't easily happening.

The flapper cables/cranks that the Red lever controls are on the firewall side of the boxes, as opposed to on the front side which would allow easier access. There's no room to get a hand back there. Add to this the fact that the linkage between left to right boxes is the other Bowden cable that Gazzer mentioned which runs behind the blower plenum, I can't tell which flapper or cable is the one which is binding up, left or right side. Unfortunately, it looks like there's no alternative but to remove all the hoses and the blower. I'm off to study up the thread that someone posted (if I can remember the title) which has a bunch of photos of the process. I guess I know how I'll be spending this day after the day after Christmas. At least it'll keep me out of the stores.

[donagain1]

Update:
With the help of a 6 year old thread submitted by Dkennel outlining the procedure to easily remove the fresh air blower/plenum, I was able to do so. This provided some much needed space though which to access the firewall facing bell cranks on the heat diverter boxes. Removing the Bowden cable's core from the crank on the driver's side proved that my binding issue is not between the dash control lever and that crank, but the crank and it's linkage to the passenger's side is a bear to operate by hand or even a pair of pliers to add some leverage. I suspect that the problem might be with the interlinking Bowden cable (which runs behind the blower unit), as there isn't a heck of a lot to the flappers themselves.

So, today's question deals with the Bowden cable. Are they available anywhere? Failing a like for like replacement, has anyone had any luck sliding the wire core out of the guide tube and removing corrosion / lubing it / catheterizing it back together (sorry for the imagery)? Also, are the clips which secure the cable to the mounting bracket trick to R&R? Thought I'd ask before rushing out to pry things apart, mainly because it doesn't look easy.

Don

[frankc]

I just saw this thread and realize that it is too late now, but for future reference if you want to see if the doors/diverters in the distribution boxes are moving, you could simply remove the grilles at the top of the footwells and peer up into the distribution boxes while operating the middle and lower ventilation controls (the grilles are attached to the bottom of the distribution boxes). There are two doors in each distribution box - the front door is for cowl fresh air, and the rear door is for heated air.

Regarding the clips securing the Bowden cable casing, they are a bit tricky to remove if you don't have a lot of access, which is why I prefer to remove the footwell grilles allowing the boxes to be flipped onto their side to access the clips in the back. IIRC, re-attaching the clips is easy by squeezing them together with a pair of pliers.

[gazzerr]

Good idea about removing the grills under the dash. I forgot that I did do that too. I was rewiring my front end at the time so I had the whole ventilation setup in the frunk apart.

I did not attempt to remove the wire from the bowden tube. Apparently that's not easy to do because you have to remove the cable from the lever box on the dash side. I've heard of people using a lawn mower throttle cable as a replacement. You can get the clips from Stoddard (sorry Pelican). I bought a handful of them because once you remove and put them back on a couple of times they tend to bend a bit and don't grip as well. Like frankc said you have to squeeze the bottom of the clip with a pair of pliers to put them on. A pair of right angled needle nosed pliers helped me a lot. Search on "fastening clamp for heating/ventilation cable" 901-571-919-00. I lubed the ends of the cable sticking out of the bowden tubes with some WD40. That seemed to help a little bit.

[javadog]

I'd try lubing the cable first. Go to a motorcycle dealer and buy the little device that clamps onto a cable housing and allows you to squirt lube into the housing. Use something made for lubing cables and do it generously at both ends. You might just have a stuck cable.

JR

[donagain1]

Ah man, this is why I love this forum. Nothing like getting clues from guys who've tread the same path before! That's a good tip regarding the vent grills, however from the airflow before I started this I knew the flappers were operating, just tough to move the lever. Things are pretty much disassembled now, and the flappers are a-flappin' freely. This puts the binding troubles in the interlinking Bowden cable. I'm going to clean it up, and try to slowly drizzle some Tri-Flow with Teflon down into the casing. I'm sure the clearance with the wire core is pretty tight, and I do NOT want to pull it out of the core and not be able to slide it back in. I'd guess that the only way it would is to grip it with pliers and coax it back through, but it's probably best not to scar the wire with the pliers. I shall see. Thanks for the tips, guys!

[javadog]

The clearance in the cable isn't all that tight, yours is probably just rusty. Easy to get the cable out of the housing and easy to put it back in...

Or buy one of these and inject some lube into it:



You can remove the cable and remove the rust with a Scotchbrite pad, or just run it through the housing a bunch of times and let it do the work for you. I usually remove the cables, clean them, clean the housings and spray parts cleaner through them, then lube the heck out of everything with a suitable lubricant made for cables, or a light grease. I don't use stuff like WD-40.

If your cable or housing has any kinks, straighten them.

It's not hard. Probably took me longer to type this than it would have to clean and lube a cable...

JR

[gazzerr]

That's a cool tool. Thanks for the tip javadog. I had never seen that before. Always learn something here. Do you remember what cable lube you used?

Don I do remember that the flappers on each side have to be perfectly synchronized in their motion or the lever just binds up. If you really push it the lever the bowden clips will fly off .

[javadog]

I have a half dozen different lubes; which one I use depends on what the cable is doing, how it is oriented and what it's on. I use Tri-FLow on some things, other motorcycle-related cable lubes, white lithium grease, other light greases, waterproof greases, etc. What I intended to point out was that some things, like 3-in-1 oil, WD-40 and various penetrating oils aren't necessarily the best choice for every use.

JR

[gazzerr]

Thanks for the advice. Yes penetrating oil was a bad idea (live and learn). I'm glad I didn't spray that into the tubes. I did use a little on the metal "L" pivots on the flapper brackets. I'll check out the Tri-Flow. Thanks!

[donagain1]

Got the cable off and it was pretty well stuck. I worked the wire core out and could see and feel the corrosion on it. Used a Scotchbright and wiped it down with Tri-Flow. The little red tub on the can mated up well with the end of the housing, so I shot some through it, and the wire slid through like butter.

Now the real be-atch is trying to feed the wire trough the hole in the pinch bolt with the driver's side air box still in place. Trying to wiggle and tug it enough to free it from the paper-ish not-so-accordion-ish hoses. The front bell crank rubs up against the brake booster, and there's minimal maneuvering room. Has anyone had their's out? What's the trick? I wouldn't have to remove it if it wasn't for feeding the wire through that bolt by Braille being near impossible. Ideas???

[javadog]

I've had these in and out many times. Usually I remove them as an assembly. I don't remember any tricks, per se, I just do it.

You might climb in the trunk and find a way to make yourself comfortable. Pile some blankets in the middle and lay on them, so you at least don't have to strain to support yourself. Have a good fluorescent light snaked back in there to give you plenty of light. Have a helper hold a mirror so you can see what you are doing.

If you remove the grills from the bottom of each housing, and loosen the clamps on the ducts, you can usually wiggle them around some.

JR

[gazzerr]

Ha yes that's a be-atch for sure. You just have to swear like a guy on the docks and keep at it and get the wire poked through the pinch bolt. On the heat side you can pull the whole assembly out by undoing the fasteners under the dash like JR said and lift the whole flapper box out, get the wire poked through the pinch bolt and and re-install. I've done it with it installed and with it removed. It's an extreme exercise in patience with it installed for sure. Small right-angled pliers and light and mirror held by the Mrs really helped I remember that. I'd love to know how they did that at the factory. Now you've got me tempted to pull mine apart again and lube it up with the Tri-Flow. I'm trying to forget the pain of reassembly ...

[javadog]

I think at the factory they put all of the pieces together on a bench or jig, then put the whole thing in the car at once. Most of the car was assembled that way.

JR

[donagain1]

Gazzerr and JR, you guys have been helpful for sure. The passenger side air box came out like a dream, mainly because the A/C wye & hoses were out, as was the fresh air blower assembly. Lots of hand room that way. Despite it being a mirror image of the driver's side, it provided a good tutorial on the sort of maneuvering necessary. Driver's side was more, er, challenging, and I don't have to tell you guys that. But, if anyone else reads this post in the years to come, they may be interested in what I had to do.

The brake booster was preventing the box from rocking forward enough to slide the upper "flex" hose connecting to the defroster vent off. The gap between the ends of the two fittings is only about an inch or so, yet the hose itself was about 5 inches long, meaning the box had to move forward about an inch and a half or so in order to slide it off enough to clear the fitting. The only way to get it off was to remove the spring clips that secure the upper portion of the air box to the main body. This was no easy trick without the proper sort of pliers. They used circlips on many of the joints of the box, but the miserable springy offset radiator type clamps on the uppers, as though they were MEANT to be removed. To pop off the rear one, I had to go through the tachometer hole and reach through with pliers. A word of caution: drape a rag over it first, those things can really fly around. After removing both it was easy to separate the upper portion from the body and disconnect it from the defroster vent. That alone increased the amount of working room to reach behind it and loosen. the cable from the bellcrank and remove the clip securing the cable to the box. After removing the front cable I was able to easily remove the box from the car.

After cleaning the boxes and lubing the flappers with silicon spray, I decided to do just what JR figured they do at the factory, sit both boxes on the workbench, and connect the cable out of the car. It made it very easy to synchronize the flappers, plus, being able to install the cable clip and tighten the nut before it's in the car was a definite plus, as was reassembling the upper part of the box with those accursed clips. By cutting an inch and a half off the upper flex hose, I was able to slide it nearly all the way onto the flange with only a minimal about protruding. That enabled my to replace the entire box, with interlinking cables attached, in behind the brake booster with adequate clearance to manipulate and position it for reconnecting the rear cable from the dash slider, and installing that clip. Plus, positioning the bellcrank for proper cable travel and tightening the nut was far easier than having to scooge around into weird positions in the frunk.

So, it's all back in now except for the fresh air blower assembly, and the dash levers operate like butter. Have to wait to replace the blower until I troubleshoot the nonfunctioning windshield wipers. With the wiper relay sitting behind the blower assembly, it'd tick me off to get it in and have to pull it back out. That's the end of it guys, Thanks again for your insight!