'86 300E Climate Control Woes

[ReverendGus]

So my 300E climate isn't controlled very well. The temp knob has no scale on it so I can't tell what the temp it should be trying to maintain is, and it seems like the only temp it's capable of maintaining anyway is full bore HOT, regardless of where the knob is.

The fan speed seems to vary, which seems right, but it seems to run slowly when it's cold in the car and faster when things start warming up - that's' counterintuitive to me.

Looking through some of the older posts I came across two things that may be of significance. One, the "mono" valve(?) seems to be a popular solution for these sorts of problems, and the other is the "temperature computer" behind the glove box. Are there any other things that I ought to be looking at?

Thanks all!

Sean