DIY page. Introduction to Resoldering Climate Control Unit - Page 7 - PeachParts Mercedes-Benz Forum

TomJ · #91 10-02-2011, 08:11 PM

Blower motor is cake, remove the kick panel (us a thin, small screwdriver to "pop" out the screw covers to avoid breaking them, they can be pretty brittle), remember the grey 1/4-turn plastic panel screws, then pull in on the black plastic that protrudes into the vent to pull the whole panel out. The motor is on the right, three 8-mm headed screws and usually one phil head lets it drop down. D/C the wiring. That's it.

Sometimes blowing the junk out of it "fixes" it.

ubertino · #92 10-02-2011, 09:47 PM

Today I started with small and easy to fix. The resistor pack checked out well. I checked the fuze, and found a mess of corrosion on all the fuzes and accompanying connectors.

A wire wheel and dremel later, and my tach is working again, and so is the blower. Well, it mostly works. Only when the cc is on automatic, and the top and bottom vent button pushed does the blower work. If either of the other fan buttons are pushed, then the blower stops. If I press the defrost button the blower stops as well. Moving the temperature controller away from max tetmp sometimes makes the center console behind the controls hiss a bit, and the fan to slow or stop.

I'm going to do the work on the cc unit, and then see. I mighty be lucky and this might fix my problem with heat.

Now all that's left is the proble of all the small holes nibbling at my car.

Marky Maypo · #93 11-26-2011, 09:42 PM

Patbob
Thanks for the detailed pics. I also visted your blog site great information a great help for 10 thump newby! I have '82 300SD.

Quote:

Originally Posted by patbob

and on...

Attachment 48576
remove bottom cover. Three tabs (yellow circles) and then it hinges off.

Attachment 48577
With the front finally off, the fan switch unit can be removed -- squeeze tabs together gently jsut until they clear and the unit can be removed. It unplugs from the side of the ACC like the temp wheel did.

Attachment 48578
Phew. Now the cover hinges up and off from the guts. The black plastic side pieces that fit over the pins slide off over the pins. Leaving you with...

Attachment 48579
..this. Well, not exactly this, I forgot to take pictures of the inside of the w123 ACC unit when I got this far, so here's a picture of my w126 practice unit. The w123 ACC has only four relays and the circuit traces are different, but otherwise it looks the same. In this picture you can see the four circuit boards that make up the unit -- the main board on the bottom, the daughter board above it, sandwiching the button switches, and the two side wing boards.

Attachment 48580
And here's what a cracked solder joint looks like. All of these are cracked. I even slipped a piece of paper in between one to demonstrate. For me, these were visible with only the bottom removed, but others have reported that the button switch solder joints on the daugher board sometimes break, and you can't get to them without a full disassembly.

hope this helps

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