In my 1995 850 with dual climate controls I do not get warm air from either of the middle dash vents when the dash/floor/mix selector is on Auto. It is 20 degrees outside and the temperature controls are on about 75. There are no fault codes.

From a cold start, after a few minutes the fan blows pretty hard, with a strong stream of cool air from the middle and some warm air to the floor. As the car warms up the fan slows but the temperature from the middle vents doesn't change. If I move the air output selector up to Dash air only or down to split dash/floor I get some warm air from the middle vents but it is not as warm as the floor air or the trickle from the side vents.

It seems the interior temperature sensors and the temperature controls work because by changing the temp settings it will change the fan speed and temperature of the floor/side vent air.

One strange thing: I think if I move the air output selector from Auto to dash only I get warm air from the middle vents for a while, but then it cools down. Takes maybe 20 seconds. I'm not sure about this one, but it seems like it cools off.

The Haynes manual shows two damper motors to control air temperature, one for each side. With only one temperature setting / side I can't see how I can get warm air to the floor & side vents and cool air to the middle vents. The manual could be wrong (possible) or I am not reading it right (likely).

Suggestions? If this was my 240 I'd look for vacuum leaks but I don't think the 850 climate controls work that way.