There is a problem with the overhead AC vents - no ac comes out of them when the rear controls are turned on. The problem is only the overhead vents, all others okay. What is causing this?
It sounds like the issue is in the rear blower circuit. Check fuses 10 and 11 in the fuse block and also the rear blower relay, which supplies power to both of the fuses. The other possibilities are the rear blower resistor, rear blower motor and control panel. You may want to enlist the assistance of a mechanic, such as one from YourMechanic, who will have the equipment and expertise to diagnose the rear blower circuit.