I have spoken to Enrique at Mr. MB Motors about the functioning of the air pump.

It doesn't matter what the outside air temperature is.

The air pump will come on when the engine is cold, and even when the car is warmed up and at idle. Mine does.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".