1995 740 IL

[Mile1]

I have a 1995 740IL. The heater will blow cold air and then hot air. The defroster will also blow cold, and then hot air. Even though the fan is on high speed, the velocity of the air flow is not that strong. Additionally, the indicator lights on the fan unit no longer illuminate green when you direct the air flow. Does anybody know what the problem might be? Thanks!

[jyep]

Hot/cold air- Have you checked your coolant level to ensure it's properly bleeded; may also be your thermostat.

Weak fan speed- have you checked your filters- cold be dirty/clogged.

Not sure about your fan indicator lights; could be a burnt out bulb.

Check out www.e38.org for possible solutions......good luck

[EXtech]

There used to be stepper motor recalls for those cars and software updates. At one point there was a service bulletin. Quite possible a faulty control unit also and maybe even an auxillary water pump. There is a good chance you could have mulitple problems. You could probably have TECH check for the service bulletins if you ask him nicely. Weak fan speed can be attributed to dirty cabin filters and/or pollen filters.

[TECH]

I can't find anything on stepper motor problems for that car, the only one that I know of is for the stepper motors being a little noisey.

For the heat fluctuation, as EXtech said, it could be an auxillary water pump (which is used to supply the heater core with hot coolant).
It may also be the heater valves sticking, or not functioning properly.
Is the engine running at normal temp, and is the coolant full?
It could be a control module problem as well. You'd really need to have it checked out to make sure.

For the airflow, EXtech is right about the filters. That's the most likely cause of low airflow, assuming the fan is running fine.
There are 2 filters under the hood that are easy to get to, built into the hood at the firewall.
There are 2 more inside the car for recirculated air, which are harder to get to. You'll have to remove the panel under the steering column, and also remove the glovebox. The filters are located on each side of the ac/heater case.