Bad Thermostat
heater hoses might have been disconected
Possible low freon.
Yes, the AC may be too cold in your room.
The answer to that question depends on what the rear ac is doing or not doing. Both the front and rear ac systems operate from the same compressor. If your front ac works fine and the system has a full charge your problem might be in the expansion block located in the rear of the vehicle. You can find the block behind one of the rear panels. Remove the panel and run the ac system. follow the ac lined that come up from under the vehicle and you will see that both lines run into what looks like an aluminum block. Check the temperature of the lines on both sides of the block. The line that runs to the rear evaporator should be extremely cold. If it is not chances are that you have an expansion block concern and it should be replaced. CHECK THE FAN RELAY FOR THE REAR AIR ALSO CHECK THE CONTROL LOCATED IN THE HEADLINER
THE COLD AIR WARM AIR EXHANGE DIVERTER DOOR IS NOT WORKING
Check coolant level May be a bad thermostat System may be airbound
Only change AC components when they fail. Many AC systems can last for the entire life of the vehicle, but when a part fails, you don't necessarily need to replace anything else.
DC Motor works on DC source and AC motor works on AC source
The purpose of the AC vent hose in a car's air conditioning system is to carry cold air from the air conditioning unit to the vents inside the car, allowing the cold air to be distributed throughout the interior of the vehicle.
Is the AC condenser in your system blowing cold air?
That is exactly how a heat pump works in heating mode are you sure it's not a heat pump?