HELP!! Smoked my second CCU control... - PeachParts Mercedes-Benz Forum

Chadahar · #1 12-02-2007, 03:42 PM

When i got my 380SE the CCU box was smoked in the bottom left of the circuit board. I have replaced the blower, the blower motor relay and the CCU relay. The original blower was dead, as in, direct power to it out of the car , it would not turn, commutator destroyed. Replaced with after market blower and it ran fine with the monovalve disconnected. I had my independent check and clean the mono valve and he reconnected it. Heat worked OK on the ride home but the controls were sporadic at best and I guess later that night, the CCU board burnt through a trace. No blower and only heat now if moving. (with the monovalve connected).
I took the CCU unit out this morning and I found this:

It is on the bottom left of the circuit board # 12(I mis marked as #10) trace (temp wheel side) burnt through (picture below). This trace is connected to the last relay behind the temp wheel.

Does anyone know if this is the trace that has anything to do with the Aux Water Pump? This is the same trace that burnt through on the original CCU circuit board. in exactly the same spot and the exact same damage. With this burnt through I have Zero, Zip, Nada controls for blower or anything, heat or A/C and NO heat all the time, with the monovalve connected. Just heat when traveling and only forced air from movement. This trace connects to the last relay behind the defrost button.

Indy did tell me that with the monovalve disconnected, that I would get heat all the time, blower or not(I did have heat all the time but blower would actuate with the different CCU controls and the fan buttons, with the monovalve disconnected). It was a little funky, but I attributed that to the CCU working as it should. (blower came on and off automatically).

I'm almost positive that the Aux water pump is to blame, but I am not sure. I have not checked my new blower for power to it yet as I took the CCU unit out first. I really hope that my new blower isn't fried.

Anyone got a schematic of the CCU?

I disconnected the monovalve again this morning. full heat thru the defrost vents and the dash vents, no blower. I will search for the Aux. Water Pump connection tomorrow afternoon. I looked tonight and could not find the connection.

JamesDean · #2 12-03-2007, 07:45 AM

i have a pdf that might bbe helpful...allbeit hard2 read...

http://www.savefile.com/files/1239047

&

see last page on...

http://www.savefile.com/files/1239056

hope it helps

Chadahar · #3 12-03-2007, 01:03 PM

WOW More than I ever wanted to HAVE to learn about the ACC unit. Not only did I down load it I'll print them out too.

Thanks.

I have found that one of my CCU units may be repairable and I'll try that sometime today. This one has very little damage as only two traces are smoked. the one I just took out has four traces smoked and one is on the edge of one of the wings that fit smack against the plastic frame and the plastic end caps so it cannot be repaired with a piece of wire.

mpolli · #4 12-03-2007, 02:50 PM

Hi,

I can offer general advice some of which you may already have figured out.

If the trace has burned up it is because to much current went through it. This is usually because it is driving something that has become a short circuit or the wire it is driving is shorted. So instead of that pin/trace seeing a "normal" amount of load, it sees a huge load and too much current flows and it burns the trace. Essentially, the trace has become a fuse. If it happens right away then it is a dead short, if it takes a while then it is a less than dead short. In any case, every board you put in will die the same way.

You need to fix whatever thing/wiring that pin is driving.

Chadahar · #5 12-03-2007, 03:46 PM

The downloads that JamesDean provided will be a great help. If I can read the schematic that is on that last page, then i can find out just what fried my CCU. Right now it is closing in on the AWP as it appears that the traces burned are indeed for the AWP. I have to look at the other trace to determine what that one is. It appears that the Mono valve is in the clear for now.

CamelotShadow · #6 12-04-2007, 01:54 AM

Wish I could help
but I;m stupidfied
Just kissing my lucky stars my lil wench
seems to be OK

Its hard when they don't feel well

Hope you get things striaghtened out

Chadahar · #7 12-05-2007, 01:45 PM

Ah Yes! Sweet Abigail! , At least she will be sweet once again. I found the problems that fried my CCU units. Although the Monovalve was and is in good shape(replacement kit parts, alas the motor id Dead, Dead , DEAD! and alas, so is the AWP.
Both , when power applied directly to them (grounded and straight 12 volt power from the battery) they both just sit there and grin at you. No vibration not trying to turn, no nothing.

So it was either or, or a combination of both that fried the CCU.

New Mono valve assy here we come and while we're there we'll get a new AWP too.

After this I think Sweet Abigail will again be sweet.

Amazing what a couple of alligator tipped wires will tell you when properly applied.

obwielnls · #8 12-06-2007, 10:42 AM

James Dean, Those were nice pdf's you sent.. do you have something similar for MY 87?

JamesDean · #9 12-06-2007, 03:13 PM

Quote:

Originally Posted by obwielnls

James Dean, Those were nice pdf's you sent.. do you have something similar for MY 87?

the 300TE? w124..sorry man only manuals i have are for the w201 and w126...I'l refer this post to a friend of mine i think he has a w124 manual he might be able to help you out...

Chadahar · #10 12-06-2007, 03:44 PM

JamesDean,
Are those W126 manuals on CD's? if so where can I get a set. Those were a big help in my running down what was wrong with "Sweet Abigail"

DANG! I hadn't read SPARKY STUFF (electrical schematics) for a few years. It all came flooding back Led me right to the mono valve circuit.

In response to the SPARKY dig, I'm a retired mechanical designer.

whunter · #11 01-17-2014, 01:49 AM

Quote:

Originally Posted by JamesDean

i have a pdf that might bbe helpful...allbeit hard2 read...

Savefile.com - Software, Games and Apps | Reviews, news and related information

&

see last page on...

Savefile.com - Software, Games and Apps | Reviews, news and related information

hope it helps

The links are dead.
Can you re-post the files ?

.

JamesDean · #12 01-17-2014, 08:30 AM

I'd be happy to, just have to remember which PDFs they were.. Hmmmmm. I'll have to look

Ha! Coincidentally I was just working on a customer's climate control unit for their 85MY 380SE.

They had the same problem as OP. Smoked that trace. It looks like another trace downstream of that was blown up as well, someone had repaired it previous to me.

http://imgur.com/a/Zxvub

Did OP ever resolve the problem?

big dog 2 · #13 01-17-2014, 10:01 AM

My burnt CCU's included blowing fuse #6 and a melted blower fuse box. All traced to a bad ignition switch creating high electrical resistance in the circuit.

liquiddog · #14 01-17-2014, 06:36 PM

That's an excellent link of ccu repair to the unit!

I don't have the link handy, but if you google 83-604.pdf and 83-601.pdf (or just open these from the fsm) that's the system troubleshooting info.

whunter · #15 01-17-2014, 10:31 PM

Quote:

Originally Posted by liquiddog

That's an excellent link of ccu repair to the unit!

I don't have the link handy, but if you google 83-604.pdf and 83-601.pdf (or just open these from the fsm) that's the system troubleshooting info.

Owners can dig that out of here later
http://www.peachparts.com/shopforum/2155238-post1.html

.