I took my CCU off to resolder thr connections and do not know how to get to the two boards that are under the first. I read the WIKI, but am not sure on how to proceed without damaging the unit. Heat and defrost would be a good thing to have use of right now.

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Dave
1983 300D Daily Driver

The first question is why are you resoldering it?

What was not working?

That should spur some help from the masters...

Be careful if you resolder. My system wasn't working as it should. I stumbled upon some info about resoldering so I went ahead and did it. I ruined my CCU. Found out later the CCU, at a minimum, wasn't the only problem (if it was a problem at all we'll never know because it is dead now).

Why are you resoldering the CCU? If it did fail, usually a seized aux water pump is the culprit. Disconnect the wiring harness from the aux water pump, and do the following test..........
Before disconnecting the CCU...........
Using the harness attached to the pump and your car battery connect black to positive and brown to ground. Does the pump run?
Re-attach the harness. Turn the key on, do not start the car. Set the CCU to defrost, the pump should run. Set it to any of the two buttons right of the defrost, but not econ. Turn the temp dial as if you were increasing the heat level, the pump should run.
If the pump is siezed, replace it and do the 1 amp fuse mod. Do the 1 amp fuse mod anyway. You will need NAPA # 7823101 (Marine grade fuse holder) and a 7821042 one amp fuse. Splice the fuse holder into the black wire, if the pump does seize it will blow the fuse and not toast the CCU.

Tell us more what the problem is and we will help. There has been quite a bit written about the Type III climate control on this list.

Alan

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DO IT RIGHT THE FIRST TIME, DON'T BE A HACK
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'82 240D Stick
'85 300D Auto
Drove my first MB at age 16 1960 300SL W190

Problem solved. Found and resolder a bad connection on the blower switch. Thanks for your advice.

__________________
Dave
1983 300D Daily Driver