Also be warned that the plastic "pop-clip" that connects the vacuum pod on the driver's side of the heater case to the flap arm can break. At a certain point, if you really want things to work properly, a rebuild of the heater box makes a lot of sense. You can replace the disintegrated foam throughout, replace all of the vacuum pods, replace all plastic linkages, and get a replacement/re-soldered push-button unit, blower motor, etc. See my prior posts for details. If I were to buy a diesel W126 I would plan on doing this entire procedure before expecting reliable HVAC operation. You could also consider replacing parts like the heater core, expansion valve and evaporator. All of this stuff can and will break (heater core, expansion valve and evaporator not as much), so replacing parts piece-by-piece will probably just lead to lots of frustration.

Just be warned that you do not want to break the plastic "extension arms" for the footwell flaps when you take the unit apart. It is easy to do, and the driver's side flap lists for roughly $250 at the dealer.

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1984 300 SD 384,000 Miles