F350 with Warn Manuel hubs will not go into 4wd. When dash switch is change to 4wd hvac goes to defrost. Do I have 2 problems i.e.: vacuum leak and transfer case problem? Does vacuum system have anything to do with transfer case or just auto hubs that I replaced with warn hubs? Everything was working fine for a couple of years but just tried 4wd and problems. Thanks for my help.

 

Did you plug the vacuum lines for the auto hubs?

 

Yes, when hubs installed. Worked great for 2 years.

 

You have a vacuum leak. Your system defaulting to the defrost is a sign of that, but if you have Warn hubs you don't need vacuum to lock the hubs, so I am a bit puzzled by your statement that your 4 wheel drive system isn't working.

Do your Warn hubs lock when you turn them? Why are you saying that you don't have 4 wheel drive?

 

I will check to make sure hubs are locking. Thanks.

 

Plug the vac feed to the solenoid on the fender. That solenoid may be cracked as well.