Recently my 2018 f150 lariat started only blowing air out of the defrost no matter the buttons I pressed. I ended up trying a new one from ORiley’s, but now it won’t switch really. Essentially it will blow out the defrost all the time, and feet selection turns on the chest vents and chest turns on feet or defrost. Something is goofy with it, but I haven’t found any very helpful information online. Thanks in advance!

 

1. Vehicle information - Type of HVAC?
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2. "buttons"... "trying a new one from ORiley’s" - Buttons? An entire HVAC? Or????? *If so, was it Motorcraft? And if not, that's what you will want.
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3. "haven’t found any very helpful information online" - Google [ site:f150forum.com/f118 blowing air only out defrost ]
   *Search of the 2015 - 2020 Ford F150 forum.

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dual zone, buttons referring to the defrost, chest, and floor selection buttons. Oddly enough, put the factory one back in as the aftermarket wasn’t working either and it went to working correctly again.

 

You never said what the "one" was. You got one from Oreilly's. The you put the factory one back in.