I begin tackling the ACC

[JasonP]

So I started with the most obvious, and the easiest for me right now - the fusebox, Mercedes-Benz Part No. 116 540 03 30:



I did a visual check and a continuity check on each fuse. Fuses #3, 9, 11, 14 and 15 all looked incredibly corroded. Fuse #3 is indeed burned out, as is #9. The vast majority of the fuses did not pass the continuity test with my multimeter, but I attribute that to the corrosion, and I did not want to press down harder with my test lead for fear of breaking the individual fuse.

I assume the six slots on the top (three on the left, three on the right - which are empty) are for spares.

I would like to take this whole assembly out one day and clean all the contacts, replace all the fuses.


This is what's left of the fuse list that came with the car, Mercedes-Benz Part No. 116 545 09 00:




It reads as follows:

USA version   fuse designation      
c = carburetor engine
i = injection engine
e = exhaust turbocharger      

Fuse #   Symbol   Description   
1      clock, trunk/roof light front and rear, warning buzzer, hazard warning light, electrically operated antenna, standing light right and left      
2   O   auxiliary fan      
3   O   air conditioning automatic      
4      glove compartment light, leveling system indicator lamp, stop lamp, turn-signal lamp, back-up lamp, instrum. cluster, seat belt warning system, cruise control, fuel supply shutoff valve (c), carburetor heater (c), automatic transmission, emission control, tachometer, overload protection/rpm-switch (e)      
5      parking/tail/standing right light, license plate, instrument, hazard warning flasher, shift indicator illumination, side marker lamps      
6   ●   cigar lighter, heated rear window      
7      parking/tail/standing light left      
8   O   windshield wiper, windshield washer pump, horn, optical horn (fanfare)      
9      air conditioning compressor, air conditioning automatic, switch-over valve idle stabilization   
10   O   (sliding roof), relay auxiliary fan-term. 86, relay power window motors-term. 86      
11      high beam left   heavily corroded   
12      high beam right, high beam indicator      
13   O   low beam left, fog light      
14      low beam right      
15   O   power window motor front right + rear left   
16   O   power window motor front left + rear right      
   
 8 A (white)
O 16 A (red)   
● 25 A (blue)
Δ 5 A (yellow)      




And a little surprise was waiting for me in the bottom of the fusebox (the yellow thing in the lower right of the first pic) - 3 Cooper Bussman, Inc. 8A fuses!



(Yes, my digital camera sucks).

[Squiggle Dog]

It's amazing how many troubles corroded fuses can cause. It looks like you know what you are doing. If you buy a new fuse set, go with brass fuses, not aluminum ones. The fuse connections are brass, and when you put aluminum fuses next to them, along with moisture and electricity, you get dissimilar metal corrosion. I get my brass fuses here: http://www.mercedessource.com/node/246, but there are other sources to get them.

I've cleaned my fuse box with a brass wire brush at the contacts. I also like to put a dab of dielectric grease on each end of the fuses to prevent corrosion. In fact, I use that stuff on every electrical connection, even light bulbs and battery terminals. Just make sure you don't put on too much, because I think it can conduct electricity from a negative to a positive connection.

If you can find a new fuse diagram ($6 at the dealer), it would be a good idea to laminate it.

[JasonP]

Squiggle Dog,

You just answered my question as I was posting it.

Thanks!

[JasonP]

Success!

I took a better look at the fuses, replaced #3 and #16 with the spares, and re-set #6, which for some reason was detached from the end (but the fuse itself is intact). Now the Defrost works!

I really do not know for sure which fuse did it. I suspect #3, "air conditioning automatic."

The right rear window is still dead as a door nail, so later I will have to wire trace all the windows. Some of the windows seem to be regulator-problems, but I think most are just bad connections.

Sweet.

Next on the shopping list: the brass fuse set recommended by Squiggle Dog, dielectric grease, and a soldering kit with electrical contact cleaning materials. I am going to completely restore the fuse-box and fuses to pristine condition, and have the materials ready to do electrical work.

[1980sdga]

I have seen plastic and ceramic versions of the brass fuses. Try to get the ceramic ones. Like squig said, dielectric grease is your friend 

[caleboar]

I'll throw in my ACC amplifier question here too.


I only get hot air through the vents. Hi/Lo/Def/Fog/off all work and push through the appropriate right vents (except center face), but no cold air.

This also happened a few years ago but was repaired after I replaced the servo (with an aluminum body) and amplifier. Well, it just happened again.

Anyway, I'm hoping I can get away with just replacing the amplifier, and not have to track down another servo (or go all electric).

But I guess my question is, if my amplifier was fried, would all of the Hi/lo/def/fog buttons still work? Or does that not matter.

[Squiggle Dog]

I'll throw in my ACC amplifier question here too.


I only get hot air through the vents. Hi/Lo/Def/Fog/off all work and push through the appropriate right vents (except center face), but no cold air.

This also happened a few years ago but was repaired after I replaced the servo (with an aluminum body) and amplifier. Well, it just happened again.

Anyway, I'm hoping I can get away with just replacing the amplifier, and not have to track down another servo (or go all electric).

But I guess my question is, if my amplifier was fried, would all of the Hi/lo/def/fog buttons still work? Or does that not matter.

I don't know much about the ACC besides the DEF portion, but when the amplifier fries, even DEF won't work because it shorts out the connection to the blower motor.

[Squiggle Dog]

Good job, Jason. It's good to start with the simple things first, and even better when it ends up actually being something simple.

[Irishflyer]

The valve I will be using to bypass my cracked servo is a Napa heating Valve with a spot to attach a cable (also available at Napa).  The part is about 24 bucks.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_6601140_0265435015

I will be routing that this weekend...mine just blows hot to DEF.  All the way hot.  I have pondered making beef jerky in the car from the excessive heat..

[JasonP]

Thanks, Squiggle Dog. I plan on taking this the whole way, so I want to cover every part of it, from the ground up.

Irishflyer - I'll keep that in mind. It may get hot out before I can get the A/C going!

[JasonP]

Heat from the dash.

Okay, so the AC has not been restored yet, but two things come to mind as I drive:

1. How do we stop the heat coming from the dash? Is there a switch or setting that stops this, or did MB just decide that the heat would always rise from the dash, and that the AC would overcome it? I doubt it, but I find no way to stop it, since it is just heat coming from the engine coolant mechanism under the dash. And no, the blower is not on.

1a. If I lay a nice fabric down on the front dash, covering these vents from which heat is contantly escaping, will that trapped heat damage anything?


2. Ventilation. How do we just open the vents so outdoor air comes in, and flows through the car? No heat, no AC, just fresh air, coming through the vents, with no windows or sunroof open.

Thanks.

[Squiggle Dog]

That big, complicated servo under the hood acts as a coolant shut-off valve that prevents hot coolant from entering the heater core. When the air conditioning is turned on it tells the servo to stop the flow of hot coolant, therefore no more warm air will rise.

When the ACCII is on the AUTO setting, the servo opens and closes enough to let just enough hot coolant into the heater core to maintain the desired cabin temperature. In the meantime, you can replace the servo with a simple shut off valve. The ACCII is a rather complicated system that takes a lot of familiarity to repair, but it can be learned.

I'm not sure I know the answers to your other questions.

[JasonP]

So, time and money has prevented a full restoration of the ACC in time for summer. I have a parts car which came with a manual heat-exchanger shut-off valve, in order to prevent heat from the dashboard during hot summer days: (the text denotes where the hose goes)



On my daily driver, I want to install this thing. I thought it would be a simple swap. Not quite. The pathways are different:



And not only that, my car has some kind of relief valve, that drained a little coolant when I opened it up:



I do not see this in the engine manual. I don't know what it is, or what it's purpose is.

(As a side note, I think it would be great if the circuit diagrams on these Merc manuals, whether they be of hydraulic, air, fuel, or electrical systems, could be matched with actual images of the car. Knowing where the line is on a diagram and which hose/tube/wire it refers to in your hand are two different things).



So, I really do not know which hoses to connect to the red shut-off valve from my parts car. The circuits are not identical.

Here is a photo of my coolant pump, for shits and giggles:



To make matters worse, I think my coolant is running low. It is below the half-way line on the coolant tank, and my engine is running above 175 on temperate (60's and 70's) days. Which coolant do you recommend I purchase to top it off?


Thanks, as always.

[TJ 450]

With the coolant,

Zerex G05 or MB Blue coolant are the only ones to use, as they are formulated for optimum corrosion protection.

Tim

[Squiggle Dog]

That relief valve with the cap on it is actually one of those aftermarket Prestone Flush 'N Fill Kits. You actually attach a garden hose to it!