I've read the thread on the DIY page, and it said there are 3 circuit panels.
On my 83 300 DT, it looked as if I have only one panel, so I don;t know where to resolder, other than the the whole thing. Took the Ohm meter out, and didn't seem to get any short circuit.
I do have erratic AC behavior, with hot air blowing out in the middle of AC running. The monovalve is OK.
Thanks for your help.
David

there are three.........one big one in the center adn two small ones butt soldered on the sides...........that butt joint frequently cracks..........

leep in mind its not a sure thing...........capacitors dry out with age and charge their characteristics.......which casues some of the problems.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Thanks so much.
I see them now. No cracks, but I'm just going to put more solder on these to see if that would help. I'm thinking of doing that without removing the blower and the temp dial.
David

If your CCU resoldering doesnt solve it a failed temp sensor aspirator suction fan has the effect of making A/C behave erratically. Its located behind the air vent next to the glove box. It should be always pulling when ignition is on and if it fails its cheap to replace. It was the cause of my A/c blowing hot then cold erratically.

good luck
Keith

You don't need to remove either the blower or temp dial. Just reflow each solder pad at the relay and add a slight amount more solder to help the reflow. Don't add too much as you may flow onto other adjacent pads. It would be best to remove the solder at each pad and reflow with new solder.

Of the three mid-late 80's diesels I have, only one climate control push button unit had what might have been a bad solder joint. The ultimate problems with the systems ended up being non-working temperature sensor aspirator motors, leaking vacuum pods, and bad temperture control modules.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

I've had one that resoldering fixed. The quick indicator for me was I could hear the relays clicking on and off rapidly while going down the road.

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85 300CD
83 300TD
78 240D (daughter)