Not too sure where this fits since these are two completely different problems, so Mods feel free to move where you think it should be

Like the title says, I recently picked up an 86 NA 2+2, fully loaded with 119K miles on the clock. I have a couple annoying issues that I just can't seem to find answers for. I've downloaded the FSM, been searching the net for a couple weeks, tinkering and testing on it and still no luck.

The biggest one seems to be a very common problem, but I have yet to find a solution (yes I have used the search and read countless threads to no avail). The blasted digi speedo only seems to work when it wants to. One minute it will be working, and the next it will just go to zero and stay there. I did notice it seems a little jumpy when it's working also. I was hoping someone here could point me in the direction to get it working right. I'm pretty short on funds, and a new sensor is ungodly expensive , so hopefully there is some little trick that someone might know to help me . All the other gauges seem to work just fine.

My other problem is the heat. It has the auto climate control, but I have no hot air when the vac line is hooked up to the water valve. When I unhook it, I only get hot air to the defog vents and cold to the floor .

I do have an account on another Z forum, but figured I could use some fresh eyes on the problem. Any help will be greatly appreciated!!