1994 900S, Dashboard, Climate control area.

Can you describe "quit working" a bit better? It's a vacuum "switch", if the hose cluster came off the back you'll probably be hearing hissing and possibly have running problems due to a large vacuum leak.

4 vertical screws (torx) visible from underneath the dash face. Undo just the right 3 should be plenty. Watch that when you pull it out you don't also disconnect the hot/cold valve shaft from it's valve on the firewall. Take out the left speaker grille in the dash so you can see what you're doing by looking through the windscreen.

Having 8 foot long arms helps as well.

What likely broke is the heater control rod.

IIRC, it does come out as a group, but I had to remove the center console to gain access. It wasn't that difficult, and I may have taken apart more than I had to. I believe if you remove the rear ash tray, there are a couple of 10mm nuts there. The area where the ignition switch is just snaps off, maybe three screw underneath to secure console. The shift knob does not come off, but you can unhook the gaitor at the base where it attached to the console.

The control setup is strictly mechanical, no vacuum controls involved. I think Dave was thinking you had a C900, instead of a NG900.

Hope this helps,

Jim M