Fixing one’s climate control

I couldn’t find a detailed guide to this, so I made one just in case.

The W123 HVAC is pretty funny, because half of it relies on vacuum actuators and stuff (if your center vents don’t work, that’s why), and the other half relies on PCBs soldered at 90° to each other and then subjected to (usually) diesel vibration for 30 years. Failure of the latter can cause the HVAC not to come on, to come on sporadically, or to come on full-heat or -cool. So re-soldering is a good way to go. Let’s do that…

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