Dash area cold air leak-source?

[Russell]

I have cold air leak around the radio and heater/ac controls. it is most noticable when teh fresh air vents are closed and dash and floor controls are open and blower is set to 2 or 3.

I suspect three things at this point. The heater box or duct has a leak or a "cold air" flap is not closing.

Is there a cold air flap that contols outside air from even entering the system? Perhaps outside air always flows through into the system.

Not a major issue. just irritating? Any heating and cooling experts out there?

[shogun]

I disassembled one IHKA from an E32 completely just to learn about the systen.
On the E32 there are 2 flaps outside left and right of the blower fan. On the left (driver side) the flap is controlled by a stepper motor, the other side is controlled by a bowden cable connected to the left side.
http://bmwe32.masscom.net/johan/ihka/ihka.html
all E32, but I assume the E34 is the same system

See # 17, and there is also a mixture flap #20
http://img357.imageshack.us/i/klimaeinheit1gt.jpg/

The outside temperature feeler next to the blower fan is NTC at 20 degree celsius 1230 Ohm
the 2 temperature feelers left and tight of the center console are NTC at 20 degree Celsius 12400 Ohm

[Russell]

Thanks. that is one scary/complex system. Mine is not automatic so it may be simplier.

[Tiger]

I am not sure... but did you know the vent right above the radio is temperature controlled by the vent knob only? There is red and blue mark that if you turn toward red, it will be warm or hot air... and toward the blue... cold air. I think it is the same for the vent on top of the dash...

[Russell]

Thanks- I was aware of that and the blue/red dial does work to modulate the air temperature from the dash vents. However, there are unwanted air leaks. Just trying to source them.

[Tiger]

I would check the microfilter area... it can leak there if cover is not on right. If no engine smell, then I'd say maybe blower area if you replaced the blower.

[632 Regal]

I discovered something with my car, the aux pump motor was locked up and making a horrendous sound so I disconnected the electric to it. Now the middle vent always blows cold air now but when the pump was hooked up I would get warm/hot from the center. No difference where the little dial is, always blows cold.

[Russell]

I would check the microfilter area... it can leak there if cover is not on right. If no engine smell, then I'd say maybe blower area if you replaced the blower.
excellent point re the microfilter. i changed it last summer. Blower motor is original.