hi guys I have a e220cdi aventgard 2007 merc I am getting a slight smell when the fan is tuned on for heating or cooling, I think the air filters need cleaning or replacing can any one guide me where the air filter or filters are located and how to access them pls. I have located the pollen filter under the bonnet and cleaned it out. the smell is still there? i would like to thank every one in advance for all your help is highly appreciated regards Bil. 
