Well, ya'll have been so helpful thusfar today, I'll troll again for wisdom.

Same 300E as I thought burns too much oil (turns out it's probably normal consumption) has extremely poor temperature control in the people tank. I understand that this is "climate controlled" and should try to maintain a constant temp by automatically adjusting the heater and/or AC.

To begin, the temp knob has no markings, so I can't make a judgement as to what temp it should be trying to regulate. That's ok, were it not for the fact that the only position in which it seems to produce any heat at all is in the fully "up" position. I assume that this is the equivalent of the highest temperature marked. Any other position results in very cold temps in the car. (Very cold is relative, however, 65 degrees here in California is freezing to most of us, but that's downright warm for other places.)

The fan does vary in speed, but no consistent temp is maintained, regardless of how it blows.

I've seen in other posts 2 things that seem promising. First is the "mono" valve and the other is the "temp controller" that is behind the glovebox (though this was described for a '85 300TDT - similar to mine?)

Are either of these two things likely culprits and reasonable candidates for replacement? Other ideas?

Thanks!

Sean