Our 2006 usually hums when it is happy which it usually is on the highway, less so in traffic.
In most cases a whistling noise only when driving is from a defective or poorly installed door gasket or a misaligned door, typically one of the sliders.
My whistles too on a sunny day, but only when everything functions well, but that doesn't happen very often. My wife said, the van is happy and what is wrong with that ?
Ford Freestar was created in 2004.
I would check and see if you have a transmission or PCM problem.
( 26 U.S. gallons ) for a 2004 Ford Freestar
One reason a 2004 Ford Freestar may stall out is because of a water damaged PCM. This is a common problem with the 2004 Ford Freestar.
According to the 2004 Ford Freestar Owner Guide : ( 26.0 U.S. gallons )
how can ford freestar 2004 water pump be replaced
On a 2004 Ford Freestar : The transaxle ( transmission ) is located in the engine compartment on the drivers side . It is bolted to the " rear " of the engine
there is no coil on 2004 freestar 3.9L engine. it is only an ignition module and it is located in the back of the engine by the firewall.
According to a website I was looking at : For a 2004 Ford Freestar ( 3.9 and 4.2 ) ( 15 city / 21 highway , miles per U.S. gallon )
There is not a drain plug on the Freestar - a good old fashioned siphon hose will do the trick.
35 lbs
inside the vehicle firewall