Does any one know why only cold air blows out passenger side when I try using the heater. Heat works on driver side. It's an 06 4x4 ? Also noticed vents won't switch to defrost from face. Any help on either issue would be great!
It could be a blend door actuator, you may want to see if you can hear it try to move when you change the blend settings. I'm not sure if that system works off of vacuum at all; if it does, check for a broken or possibly a disconnected vacuum line along the firewall or under the dash. Hope this helps you out.
Actuators are probably out. You will usually hear a clicking under or in your dash whenever you change your temp.control or air flow control most of the time both go bad about the same time.
Very common problem with the first gen.Titans.
There are threads on here about this and what to do about it. Check out the thread, That a knowing clicking under the dash.