inside aircondtioning blower will come on when switch on, then go off for a few.

I'd recommend finding a shop that specializes in Mercedes. The Crossfire is basically an early SLK with different bodywork, and most Chrysler techs will be lost on it. Be prepared to pay a Mercedes-sized repair bill, too.

This may sound highly improbable but I appear to have cured the same problem by just fitting a new cabin air filter - 10 minute job, having only bought the car last year with 65000 on the clock I doubt the filter had ever been replaced before.