'99 Clk320

[Lucas1]

I'm trying to find a DTC description and diagnostic steps for B1421. I'm currently in school and am taking an auto climate control class. We have to do a presentation, as a part of our final, on an Auto HVAC sytem and I chose this car since my mother-in-law has one. The information available on Shopkey and Alldata, which we have at school, is VERY limited. I can't even find what sets the DTC or what the symptoms would be. It looks like it has something to do with the condenser fans, but I can't find what.

If anyone could help me out, it would be great. I need to know: 1. A description of the DTC, 2. Conditions for setting the code, 3. Steps to diagnosing the code, and 4. Possible repairs needed to fix the car.

Thank you

[CLK320MIA]

B1421: Auxiliary cooling fan

Disconnect A/C push-button control unit connectors. Connect socket box to A/C push-button control unit right connector. Connect DVOM negative lead to ground and positive lead to socket box terminal No. 16. Turn ignition on. Press both AUTO buttons and hold down for a minimum of 10 seconds. DVOM should indicate greater than 2 volts. If readings are not as specified, check auxiliary cooling fan circuit. See WIRING DIAGRAMS. If circuit is okay, check AIR control module. See FIG.2