Only one Serpentine Belt in this model, Eric.

Search for Klima and check out post by stevebfl he describes its function there.

The Klima relay is to protect the compressor in case it has any low pressure conditions in the W124 and other models, as well as protecting the engine I think, because if the belt siezes that will stop the water pump and alternator at the same time (then you got big problems instantly, like engine failure!)

The old style AC in pre-Serpentine Belt cars, left one with the option of cutting a V-belt if the compressor siezes up (sometimes the clutch siezes up on them and the belts smoke and squeal bad) and continuing to run with no problem.
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!