Good day everyone-

Car in question is a 98 S500 with the activated charcoal filter (if that matters). The problem is that regardless of the selected fan speed setting shown in the LCD, the air flow does not seem to change. I stumbled across a website, www.continentalimports.com , that shows the three diagnostic tests that can be performed from the push-button controller. The three diagnostic forms are: (1) Actual Value- provides information on many different things including evaporator temp, engine temp, inside car temp, blower motor voltage, engine speed, heater core temp, refrigerant temp, vehicle speed, refrigerant pressure, battery voltage, etc. (2) Fault Codes - highlights any fault codes or errors in the system; and (3) Mode Activation - AKA Individual flap tests providing the ability to direct airflow to each outlet to ensure that the flaps are working properly. I followed the steps to enter each of these diagnostic modes, but was unsuccessful at getting into the Fault Code mode. However, when I was in the Actual Value mode I was able to see the voltage going to the blower motor, which I was able to manipulate with the fan speed control from low (.8 volts) to high (6 volts). Although the system showed that the voltage was changing with the selected fan speed setting, the air flow remained unchanged. What could be causing this? A bad blower motor? A faulty regulator? Some type of sensor?

While the article on continental imports was helpful, the examples were done using a 210 chassis E320, which for one does not have the activated charcoal filter. I found that in the Actual Value mode there were some additional functions that the article did not discuss that were shown when I was in the diagnostic mode. Also, I was not able to enter the Fault Code mode. Here's the method that the article said to do to enter the Fault Code mode: Turn on the ignition and set the left temperature to "HI" and the right temperature to "LO". Then, simultaneously press buttons "Rest" and "EC" for five or more seconds. All of this must be done within 20 seconds. The "Recirculate" button will flash its LED. The screen will then go blank, and the first code can be brought up by pressing the right "AUTO" button. When I completed this sequence, the system went into the Actual Values mode instead of the Fault Code mode. By contrast, the article states the following for the sequence for the Actual Values mode:
Turn on the ignition, press the "AUTO" button, set the temperature to 72degrees F (this can be done quickly by pressing both the red and blue arrows at the same time), then press the "REST" button for five seconds or until the left-side display reads "1". My summation is either the article does not give the correct sequence, I'm an idiot that can't follow directions, or hopefully the Fault Code mode does not come up if there are no faults in the system.

So can anyone answer the following:

1) Why isn't the fan speed changing with the control button?

2) How do I get into the Fault Code mode?

3) Does anyone have or know where I can find the Charts for the Actual Value code showing the normal values and the Chart for the Fault codes explaining what each code means?

My apologies for the long message, but thanks for listening and thanks inadvance for any advice that you may give.

Michael