You have the digital temperature controls and the little doors inside the heater box(behind the dash assy) are broken. The only way to repair this is to pull the dash and the heater box assy out. This will not be a cheap repair--at least $500.00-$1000.00. Sorry for the bad news.
It begins at the intake manifold.
the heater control valve or DCCV (dual climate control valve) is located next to the radiator on the passanger side just below the high pressure side service connector
the engine control module (ecm) is located behind the passanger kick pannel. which is located by the floor, passanger side.
TAke it to the dealer where they have the proper machines. That last answer really sucked, spoken like an union mechanic. Go to this link: http://www.justanswer.com/questions/1jjd3-2000-grand-cherokee-split
Go to www.wjjeeps.com and type HVAC in the search box. All the instructions are there.
No the climate control is tied into the electronic control system of the car which is controled by the computer. The climate control can also be used to view or display fault codes from the computer...............
need more information, what year, do you have duel climate control, give me a little more information. If one side is hot and one is cold, you have a distribution problem in the dash. Could be a loose fitting, a broken airflow control door, a controller issue, etc. i don't have dual climate control. 06 jeep grand Cherokee
Climate Control - 2016 was released on: USA: 2016
Dual Zone Climate Control: -It is possible with dual zone climate control that every passenger in the car can have separate air conditioning temperature.
the power control module is located on the passanger side of the car above the plate where the carpet meets the dash.
It's on the passanger side in the engine compartment above the wheel. Follow the front throttle cable right to it.
The 1993 Jeep Grand Cherokee engine control module is located on the firewall in the engine compartment. The engine control module will be on the passenger side of the firewall.