The climate control in the E36 M42 318is I just imported from Japan was intermittent. It either worked perfectly, or the display would suddenly go blank and none of the controls would work. It seemed to hold the last setting selected, with the heat on when I didn't want it, or the AC running when long past cool.
I fooled with it for awhile, and discovered flexing the main connector (blue/white) back and forth could make it turn on and off. I re-flowed all the connector pin solder on the board, and checked all the crimps and sockets to no avail.
My brother sent me a link to this page where they had cured the same problem by replacing a cap on the board:
http://www.macadamizer.com/bmwfix.htmlI couldn't reconcile a cap failure and the on/off behaviour I was getting by applying force to the connector, or moving the wires. It then occurred to me that maybe I was flexing the board enough to make and break contact in a broken solder joint for the cap.
I re-flowed the solder (after scraping the conformal coating off) on the two capacitor leads, and my climate control was cured!
Perhaps all the people that use that fix by replacing the capacitor could fix the board just by re-flowing the solder joints rather than replacing the cap.
It is strange that the solder joints would fracture on that cap, since it is well supported. The only thing I can think of is that the board has a resonate frequency that causes flexing while driving the car, and eventually the solder joint breaks.
You can re-coat the solder joints with nail polish for a bit of protection.
Hope that might help someone else.
Kevin
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