My ford f350

[flip]

2000 ford f350 7.3 4x4
Its stuck on defrost I have replaced vac pump both actuators under the dash vac canister still dos not work on any other setting but when i put it in 4wheel drive it will move to the position that I have selected. Any info would be great

 

[XSrcing]

You fed it after midnight, didn't you?

What year is your truck?

 

[flip]

You fed it after midnight, didn't you?

What year is your truck?

That would help ( fixed ) :awesomework:

 

[nowires]

check the fromt hub vacume lines. If the front hubs are auto and they leak it will cause it.

I have the same problem if the inner seal on the axle starts to leak. you can test it be taking a pair of vise grips and pinching the vacume line that goes to the hubs. I got into the habit, if I pull an axle, I replace the inner seal

 

[WA-Wheeler]

I don't know much about big trucks but vacuum leak would be my best educated guess.

 

[Jeepasaurusrex]

The heater is set to default on the defrost setting if there is loss of vacuum to the system. Check your vacuum pump, lines etc. Its located on the passenger side fender behind the battery. I just replaced mine for the same reason.