We just picked up at used 2000 ML320 and sometimes it can take up to 2 to 4 minutes for the fan to blow air... it acts like it is turned off, then all of a sudden it goes on. I drove several other ML's and I don't remember noticing this.

When you turn on your car, does the air instantly start blowing or does it take a while too?

Thanks

It blows right away. In the '04 loaner I'm driving now I have it set to "auto" and it blows lightly at first the after 5-7 seconds it will start to blow at the necessary speed for the temp I have set. I was surprised that even when I have the whole system off--air blows in at my feet right after ignition then stops after two seconds. Two to four minutes is obviously not normal.

I have an 02 and it turns on very quickly as well (easily under a minute)

My 02 sometimes take a while to blow. If I get in and crank up the fan, nothing may happen for a few seconds. Then all of a sudden the fan comes on and it sounds like a jet engine! Always thought it was normal.

guys, remember the 02 saw the introduction of the "auto" air conditioning. Pre 02 I think i am right in saying was purely air conditioning, not "automatic" temp setting.
Not much help I know, but I thought I would add it.