I have a 2001 E350. The front HVAC completely stopped working, but still getting good air flow from all rear vents. Checked fuses, but not sure where to go next. Not sure if it could be the blower if rear vents still work. Have read that a vacuum leak would cause it to default to the defrost setting, but that isn't working either. Any help would be greatly appreciated.
Can't really make out your issue however if there is no air flow up front it means the main blower motor has failed or an interruption of the power circuits has occurred.
That could be anything from a fuse, the dash board mounted speed control switch, the resistor network or the blower motor.
Your issue isn't to which vents air is flowing--at least not at the moment. First solve the issue or why the blower motor isn't working. You can find free and reliable schematics for your year and model chassis at AutoZone---download and print or view them there---should be easy to sign up etc.
Thanks JWA. I have noticed that once in a while the blower motor will make a little bit of a grinding noise when the AC is on. Of course the van is as loud as can be, so that little noise is probably a very big noise. I'm assuming that there are two separate motors for the front and back, although I couldn't find anything about the rear blower in my Haynes manual.