Welcome to JA Jeep my name is Mark.
Do you have automatic temperature control or the manual heater a/c system?
Automatic temperature control
The fan doesn't work in auto or in manual the temperature control allows the car to have hot air by driving. I thought that it might be a temperature control damper that closes or opens based upon outside temps
Models equipped with the optional Automatic Zone Control (AZC) system have a blower motor controller. The controller allows the selection of almost infinitely variable blower motor speeds. The controller is mounted to the HVAC housing, under the instrument panel and just inboard of the blower motor, in the same location used for the blower motor resistor on manual temperature control systems. It can be accessed without removing any other components.
Checking under the dash and having a look at the wire connector to this controller may show some overheated connections.
A new blower motor controller is your most likely cause and a new connector if there are any signs of overheating.