No it is the blower motor regulator, common failure point on that car. You can sometimes source the regulator without the motor.

Had the same issue with our 98 S500

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2001 G500 (45k and counting)
1991 350SDL (211 and counting)
1998 C43 (50k) Silver/Black (sold)
1995 E500 (40k and counting) Pearl Black/Anthracite (sold)
1991 300CE (50k and counting) Silver/Black Cloth (sold)
1983 300D - 79k Classic White/Blue Leather
2002 E55 Obsidian Black/Black
1996 S600 Coupe - 75k Black/Black (traded)
1984 300D -145k (sold)
Silver Blue Metallic/ Blue Leather
1985 300D - 87k (sold)
Manganese Brown/ Palomino Leather
2005 E55, 50k(sold)
Flint Gray/Black