Cabin Air Filter If it has one it will be behind the glove box .
Open the glove box push in on the sides and the glove box will come out the bottom hinge will hold it on behind that. There will be a plastic cover with 4 plastic tabs push them in pull the cover off and there is your CAF.
I was looking at the 2004 Lincoln Aviator Owner Guide and it does not show anything about it having a cabin air filter
According to the 2004 Lincoln Navigator Owner Guide : With engine oil filter change ( 7.0 quarts )
There is no Cabin Air Filter on the 2003 Lincoln Town Car
The 2004 Lincoln Navigator has 32 valves.
The 2004 Lincoln Navigator has a V8 engine.
The 2004 Lincoln Navigator has a 4-speed automatic.
The 2004 Lincoln Navigator is a gas-powered vehicle.
The curb weight of the 2004 Lincoln Navigator is 5822 lbs..
The 2004 Lincoln Navigator is 17 ft. 2 in. (206 in.) long.
The height of the 2004 Lincoln Navigator is 6 ft. 5.8 in. (77.8 in.).
The 2004 Lincoln Navigator's turning circle is 40.4 ft..
The 2004 Lincoln Navigator has a drag coefficient of .41 Cd.