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

It's normal for the fan to run only very slowly until the heater core warms up (approx 40 on the guage, maybe higher). This is to avoid blasting icy air on startup.

The fan will run up to full speed, then slow down as the temp comes up, then fade away quite a bit as the temp stabilizes.

You should at least have blue and red (cold and hot) temp marks on the wheel. All the way up is cold, all the way down is full heat.

Set the temp wheel about the center and see what happens. Should have no fan at startup cold, then generate considerable heat at high fan, then settle down to moderate heat with slow fan in either economy or standard auto modes. If set to defrost (farthest button to the left), you should have full heat and full fan all the time, reguardless of temp inside or engine.

On the "windshield and floor) button, (next to the defrost button), you should get normal temp control but more air on the windshield than the floor.

If you only get air out the defrost vents, no matter what the setting, you have a vac problem, either supply or bad vac servos in the dash.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!