2005 Saturn Relay , blows no air from the rear upper vents why?

What is your question?

2005 Saturn Relay , blows air through all the vents in the front of the suv ,but doe'nt blow air from the rear upper vents at all.I know their are actuators under the dash,i'm not sure which one controls the rear , or if their even the problem .The temp control modules very exspensive i'm not sure it's the ,i don't know how to check it. I'm a Nissan tech.I thought maybe someone heres had this problem. thx