This link should tell you more than you ever wanted to know about the ACC II servo: http://kittrellcommunitywatch.dyndns.org/servo
These things have a couple of bad flaws. First the plastic part is prone to cracking and leaking, especially with age. Second there is a seal of the shaft that controls coolant flow which will fail allowing coolant and crud to hum up the gears and electrical connections under the top cover. I don't know anyone who installed the unwired tools kit. George Murphy sells rebuilt units with a metal chamber in place of the plastic one. But, as far as I know, once they start to leak they are toast. -----Original Message----- From: Mercedes [mailto:mercedes-boun...@okiebenz.com] On Behalf Of Tim Crone Sent: Thursday, August 08, 2013 2:39 PM To: Mercedes Discussion List Subject: Re: [MBZ] '77 300D ACC2 widget On Mon, Aug 5, 2013 at 7:14 PM, Allan Streib <str...@cs.indiana.edu> wrote: > Alex Chamberlain <apchamberl...@gmail.com> writes: > > > What's wrong with the Unwired Tools kit, besides the fact that it's way > > overpriced for something that anyone with some electronics and > fabrication > > skill should be able to cobble together out of an Arduino and some > aquarium > > tubing? > > I think the Unwired kit pre-dates the availability of cheap, flexible > microcontrollers like arduino. Someone with motivation could proably > drastically undercut their price now. But the hard part is figuring out > how all the different modes of operation work. I think there's enough > documetation of the ACC online to be able to work it out, but it would > take some time and tinkering. And the market for it is pretty tiny now > and will only get smaller. > I took this puppy apart the other night. It was shockingly corroded, and I still don't understand exactly how the vacuum part works. Not a super-complex mechanism mechanically though. (By the way, Mitch wins the first question; I was able to put a #10 in the bad slot and it is now air- and hopefully water-tight.) The main section, the big round part that is cracked, has a 9-or-10-gear reducer and a motor in it. It distance-limits the turning of the gearing with a peg through a plastic gear, and all but one of the other gears in the reducer appear to be copper. The gear farthest from the motor is in the middle, turns the fastest, and has a friction coupling to a screw-and-gasket. This last moves up and down, in conjunction with a small "straw", to let more or less water from the main channel [which I assume is pass-through to the radiator] to the small channel [which I assume goes to the cabin]. I could not get a strong seal even with the screw all the way closed; so either the rubber is old or there is supposed to be a very small amount of water movement even if the AC is on. All my gears were completely frozen, both with corrosion and ancient grease. I was able to pull two locking rings off the gear assembly, and one of the gearsets pushed out the bottom. The other was stuck until I pried up the center gear, which sits on a friction ring, then I could knock the remaining gears out. The casing is a pair of flat metal pieces that screw together, functional but again not complex. The motor has two leads. Mine are broken off, but it looks like a standard 12V motor so the pegs should be on the end somewhere. There was a capacitor (?) across the terminals, at one point, but it fell off many years ago and has too much corrosion on it for me to identify. I haven't decided if I want to try to fix the motor, I'm quite sure the alignment on this whole thing is way out of whack. At the top of the gearset there is an armature that moves back and forth between a maze of contacts. It looks like this maze determines the direction of the motor. The armature rests on a switch, and the switch has a rubber piece that has another complex maze set into it. I -think- if you pull a vacuum on a certain part of this maze from above, the armature is supposed to turn into place and set the appropriate voltage for the motor. If you pull too hard (or maybe stop pulling?) then the switch will lift, and that cuts off power to the motor. There are still some unexplained things - there is a vacuum port on the bottom of the controller that doesn't seem to do anything, but has a nice gasket embedded in the plastic. I still don't understand why there are so many vacuum points in the main connection. I have no idea how the AC is triggered. There's a spring inside the big channel that I can't explain. Probably some other stuff. I didn't find as much vacuum stuff as I was expecting; there was a bank of right-angle connectors, but that's all I came across. It may be there is some channel thing between those and the armature that I haven't figured out how to open, yet. Unfortunately while I was taking pictures my phone got full, so I don't have many. As I go through to grease, solder, and close it up I will try to get more, in case someone else wants to try it some day. Best, Tim _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
