Fuse 27 on my truck is for the vac pump. First indication of a bad vac pump for me was the turn signals stopped working. Still had hazards, just no left/right.

Oh, and guess what is not listed in the owners manual fuse diagram.

 

I have a 05' F250 6.0L, The Ac blows thru the defrost... It must be the the vacuum pump or vacuum lines, How do I check for leaks in the lines? I checked the fuses they all seem fine. its going to be very hot this week now I want it fixed.. Any help with this would be great thanks.. My truck has manual hubs and 4x4 selector.. Not a leak there...

 

I had Defrost only too, although the hot/cold air still worked. I pulled the connector and there was power to the connector. My vacuum pump motor was bad. I found one at ROCKAUTO.COM for ~ $65, Dorman brand. Replaced it and the pump would not stop running. It made lots of noise. Fortunately, the leak was in one of the hoses in front of the pump. I got lucky and one of the hoses I pushed on caused the motor to stop. I still need to do a vacuum leak down check just to make sure something else isnt bleeding off the vac.

The failure was caused by the vacuum line leak which caused my motor to always be running and trying to pull vaccum. Eventually it failed.



2003 6.0 Diesel F-350 Crew Cab, Long Bed, FX4 Long Bed Sacramento, Calif.