Clean air is important both for the engine in your F350 and for the passengers inside the truck. The Ford F350 is equipped with a cabin air filter that cleans the dust and particles out of the air coming into the truck through the HVAC system. Like all filters, this one requires periodic maintenance. It should be changed at least every 10,000 miles or once a year. The filter is located behind the dash on the passenger’s side of the truck and can be changed with a single screwdriver. Purchase a replacement filter at any auto parts store.
Locate the cabin air filter access cover under the passenger’s side of the dash. There are five Phillips head screws holding the cover on the air duct that will make it easier to identify.