2007 F350-defrost vent problem
 

I don't know if anyone can help, but the other day I realized that vents won't switch from defrost. The blower motor seems to be working fine, it just won't switch from defrost to floor or face. Anyone else have any issues with this or know of a solution? thanks

Read the stickys about four wheel drive not working, when there is a vacuum leak in the hubs, the a/c vents default to defrost.

I thought they only default to defrost when your switching into 4wd?

That may be if the vacuum line at one of the hubs is screwed up... what if the vacuum line in the passenger foot well is the problem?

Keith

I haven't had the 4wd engaged? Would that make a difference?

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I checked the 4wd and it is engaging.

No were talking about your defrost will come on when you have a vacuum leak and try to auto lock the hubs.

Behind the glove compartment is where the air is redirected, I'd start there leak checking the line by applying vacuum to them. The one that you disconnect that doesn't hold vacuum is your winner, track it down and find the leak. If all hold vacuum, then look at the vacuum motors that open/close the doors.

are there any seals or anything inside the hub that go bad? when you manually turn the driverside hub you can hear pressure seeping out when you lock it into 4x4.

You are probably hearing vaccum leak, there is an Oring on the hub that can do it there is alo a seal on back of hub but that normally goes wen the hub bearings fail.

Are the o rings replaceable by themselves or is this also a major fix and have to buy complete hub to do this?