Hate to say it, but my money's on a bad A/C Heater Control Module ( the silver panel with all the ***** and buttons for climate )
( it talks to the BCM and tells it to run the engine fan when you press the snowflake )

Here's one for a SLK32 ( it will work ) for only $89 with free shipping : ( it's not silver, but I have seen pictures here where some members have installed it )
97 98 99 00 01 02 Mercedes SLK230 Temperature Climate Heater A C Control Unit | eBay

NOTE: There are hundreds of the silver Crossfire ones available on car-part.com, some as low as $40.
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