If you have BOTH a factory AC and an AUX Heater you will need the additional Curved Tube Support part option in order to properly install your Side Steps.
You can see an additional picture for reference HERE.
Here is a video where Brent provides full detail on the need for this extra part.
Sprinter Side Step Extra Curved Tube Support Part details
Brand: The Van Mart
Built for: Mercedes Sprinter
Buying the Sprinter Side Step Extra Curved Tube Support Part from AVC RIG