My compressor clutch spins whever I activate either the AC or the heater. The only time it stops spinning is when I push the "O" control button at the right side of the dash control panel.

Is this normal? If not does anyone know why the AC clutch spins when the heat is on?

Might there be a problem with the controls?

It will spin unless you press the EC button or the O button. Heat is dehumidified in Mercedes, hence the A.C. compressor.

Thanks Don,

I was quietly concerned about the situation.... Its a relief to know that things are supposed to be working that way.

Smiles.