2003 Jeep Cherokee Overland---Blower works for both AC and heater...however, heat is now blowing cold air. Is this the blend door or possibly some other part?

Blend Door Actuators not working properly. The doors open and close to blend hot or cold air.

https://www.google.com/search?q=2007+jeep+grand+cherokee+blend+door+actuator+location

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Jeep Grand Cherokee is notorious for broken blend-air doors. This is the door inside the A/C-heater housing that switches the air from hot to cold. You must remove the dash to repair it.

this model has a couple of possibilities, updated heater control panel which is quite an expensive guess also the blend doors located in the heater casing break also an expensive repair as dash needs to be removed t gain access, would advise dealer visit first to confirm correct fault.

Probably broken blend doors if everything else is working, but its just blowing cold air. Do a google search for "Jeep Blend Doors" or "Heater treater" for more info.

sounds like the blend door motro may be bad, this motor is screwed to heater box, there are a few of these motors one for pass/side for hot/cold air then one to control position of air like defrost or vent or floor, then the driverside cold/hot air, i think this motor is on driverside part of heater box, to make sure locate each motor while moving all controls until you spot the one that doesnt move, then remove it and move door manualy to see if you get heat, then replace that motor, hope this helps,

either bad recirc doors or a possible bad heater core. Open the hood and when the car is warmed up to mid point on the temp gauge look on the passenger's side firewall under the hood. You will see 2 black rubber hoses running through the firewall. Feel each hose and if one of the 2 are cold then you have a bad heater core. Otherwise most likely the recirc door.

You most likely have a problem with a part called the air temperature control blend door, it controls the air flow across the AC core or heater core, it is most likely warped or the motor that operates it is defective or in most cases both are in need of replacing. This repair requires the entire dash be removed to access the AC parts.

The blower problem on your jeep needs proper diagnosis. This could be one of several problems.
As simple as a relay or as big as a blower motor. With automatic temperature control you could be looking at a control assembly.

the cold air on the passenger side is a passenger blend door problem. Could be the actuator or a broken door. This problem requires removal of the entire dash to get to the problem. Not something you want to tackle without a complete step by step set of instructions.

I do have one other suggestion for this problem. You will still have to get the blower problem to complete the repair. Copy this link and go see what you think about blend door repair.

http://www.heatertreater.net/Jeep%20Page.htm

Best Wishes
Good luck

it maybe a blend door problem. if both hoses at the firewall for the heater are close in temperature its not likely a heater core. the actuator for the blend door is located on the bottom of the heater/ac box towards the middle of the bottom. it will be a tight fit but you can remove it without removing any part of the dash. take it off and disconnect the power. start the vehicle and manually move the door and see if the temp changes

Mine did the same thing. The quick fix is to turn the knob to the heat side, then push gently on the knob itself. You'll instantly feel the air get warmer. The real fix entails taking the dash apart.