Article by: Johan
Applies to: all e32 and e34 models.
Problem: There is no air coming from the rear ventilation ducts.
Background info: The rear air ducts will only blow fresh air or air conditioned air. So there will be no heat coming from this duct.
There are two wires going to the circuit board on the side of the grill. If they are disconnected the flap in the heater core housing going to the rear vents will remain closed.
Removal and fix: To remove the air grill pry out the blinds next to the cigarette lighter, or if you have rear seat heating pry out the seat heating buttons.
Then pull out the entire black panel. Now you have enough space to push out the vents from behind.
Next I removed the circuit board (if you can call it that). By removing the board I broke all plastic pins that hold the board.
The problem was easily diagnosed after this: the slider contact had worked loose. I put the slider back in it’s place and secured the circuit board with hot glue.
When putting everything back together remember that installation is the reverse of removal.
“Be careful when removing and re-installing the rear vents and electrical connecting plugs. Over time, these parts become brittle and can break easily if you man-handle them without care (ask me how I know).
Once they break, your mood will become very bad, your wife and kids won’t like you, and your car will be more broken than it was before you started.
So . . . go easy there big guy. Easy.”
~ M. Oswald