short intro:
early 1999 F-350
bought this truck knew that the blend doors wouldn't work. finally got a chance to check it out.
key on: pump not running
made sure pump was plugged in, it was
check voltage to pump- none
ran jumper wires to pump it runs and moves blend doors

now does anyone have or can tell me where to find wiring diagram for this item (vacuum pump).

is there a fuse or relay to check, I looked but didn't see any that lead me to think that it controled the vacuum pump.

since the pitail goes to the big harness running the width of the truck I don't want to unwrap it until I have an idea what to look for.

Jay

 

Are you sure there even is such a thing? I haven't worked on a '99, but in all my experience, vacuum-operated heater controls source from engine vacuum. That's strange to me that there would be a separate vacuum pump behind the dash when the engine is basically a giant vacuum pump. Vacuum-operated heater controls were originally designed to eliminate the need for an additional actuating mechanism - so a second vacuum pump would seem counter-intuitive. Maybe I'm wrong; I just haven't heard of this.

 

Yes, this pump is located on the passenger side top fender well right behind the battery. the only thing it controls is the blend doors and the auto lock hubs on a 4x4.
http://www.accuratediesel.com/shop/132.html

but no one on any of the forums (powerstroke.org, powerstrokenation.com, dieselsite.com, competitiondiesel.com and forddieselpower.com) that I have posted on can help so far.

Jay

 

The vacuum pump is powered by hot in run fuse 28, 10 amp, in the fuse panel under the dash on the left hand side. No relays or anything special controlling it. It's fed by a lightblue/pink wire.

 

Thanks Franklin2, the fuse was blown and now it works.

Jay