could be low on coolant
Either the a/c system is low on freon or the evaporator has an internal restriction....
good question
The heater core valve is probably sticking or adjusted wrong.
The blend door actuator may not be working.
Coming out of the vents around 43 degrees
The HTR RR switch in a Kia Sedona determines which air vents the air is blown through from the rear heating. When it is pushed in, the lower vents blow hot air, and when it is not pushed, the roof vents blow cold air.
most likely it's a bad thermostat, or your vents not working properly.
The a/c - heater controller is out...........
Possible blockage in the rear air units expansion valve. I just replaced mine for the same reason.
Compressor not operating.
It's somewhat cold. It's just very little cold air coming out. Can't hear the vent blow the air as well.
Check temperature control cable for binding.