Kia sorento temperature display not working

Try switching off your safety child control on drivers side door panel, if not check fuse or replace drivers door master window switch assembly

Check for electrical shorts in your control panels.

Could have a faulty low pressure switch.
The low pressure switch is located on the air conditioning line in the right rear of the engine compartment near the firewall.

The low-pressure switch in your air conditioning system is used to interrupt power to the compressor when the low side pressure drops below 25 psi. This prevents freeze-up of the system and possible damage to the compressor. When the switch is faulty, the symptoms of freeze-up, or no compressor function, will be present. Replacement is straightforward, but requires the removal of refrigerant from the system.

Sorry for your troubles ,
Temperature Hand in dash reading NORMAL ?
Does it Turn Blue to Red if so is do you feel friction or restraint like your turning something rather than freewheeling (smooth fast turning) or Digital and or does it show that it should be warm and not cold ?
Does the TEMP change at all(even the least little bit could narrow the results down) when knob is turned?
POSSIBLE - The Actuator/Motor that switches the VENTS very well could be BAD , Temperature Switch / Climate Control Switch (hot to cold could be broke at the base and only allowing the knob to turn and not in the switch ) Thermostat may be stuck open (keeping the engine running cool and smooth but no heat , maybe just a slight TEMP change when switched from Cold to Hot ). The A/C Switch is pushed in or turned on or broke and is stuck ON
FIXES - 1st- Check FUSES - If Temp HAND Reads Normal it not your THERMOSTAT. - Change the Control Switch / Temp switch - Check A/C Button/Knob . AUTOZONE is my place of business they PRICE MATCH AS WELL!
Hope this Helps , Flaming Ratchets Auto Repair

Kia tends to have rather poor heater control switches and motors. If your car has manual dials, then check any cables and fixings on the back of the control panel. These cables can come loose and fail to push and pull the armature on the heater matrix valve. If the car has an electronic climate control, then check the electric motor on the heater matrix valve as it may have failed.

check your heater controls , there may be a cable lose or broken, or a vacume hose lose or broken,i don't know if that car has a heat control valve,but if it does you might check that as well.
hope this helps!

Intake Air Temperature (IAT) Sensor: this sensor is located in the air intake plenum assembly. This sensor is combined with the MAF sensor.

Hope helps (remember to rating this free answer).

First, check your coolant if it's full, or has gone deplete because there been issue with the sorentos which kia doesn't acknowledge of a loose or leaking radiator plug which loose coolant. With low coolant, the heating system would not work since it's only sucking in air. 2) If that is not the case, then you maybe looking at a case of a plugged heater core, or thermostat being stuck open. The position of the air temperature valve in the air conditioning housing under the dash (which determines how much of the total airflow is permitted to pass through the heater) is stuck. The valve position determines the warmth of the overall air flow that is sent into the passenger compartment. This door-like valve redirects air flow. In some positions such as defrost the AC comes on to dehumidfy the air to aid in clearing the windows during high humidity. You may need to take a look behind the glove box compartment and dissemble the blower motor and clean around. It may work, if not you will need to get it to a shop as the heater core probraly bad or leaking.

2004 Kia Sorento The Wiper Relay is Part Of The IPM Module .

Its The Kia Body Control Module Should Be Located Left Driver Kick Panel Behind"..
http://www.ksmanual.com/ipm_removal-1120.html

Maybe it could be the switch it's self?