My 2005 X3 only blows air through the defrost vent. Doesnt shoot air through feet nor front traps!
Check to see that you didn't leave something un hooked. Sounds like you are having a mode door issue.
https://www.bimmerfest.com/forums/showthread.php?t=503815 -- this probably not your issue but you might want to check it out.
Dandy is right. Either a vacuum hose is disconnected or something didn't get plugged back in when the blower motor was replaced. Retrace your steps. When the climate control system loses vacuum or power it defaults to defrost for safety reasons. HTH. -Jim
Your system does not use vacuum it uses electric stepper motors to control air flow. If one is unplugged then it defaults to defrost. Also same can happen if one fails.
Looking for a Used X3 in your area?
CarGurus has 12,314 nationwide X3 listings starting at $3,500.
Search BMW X3 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
BMW X3 Experts