When starting the vehicle, the A/C control for the Rear Defrost would blink and A/C air temp blend door would operate (opening and closing) for several minutes. After several minutes, the A/C or heater would operate. I replaced the A/C control unit in the dash. This did not cure the issue. The vehicle went to the dealer and it was diagnosed that the A/C air temp blend door was malfunctioning and causing the air temp blend actuator to operate uncontrollably. This appears to be a design flaw with this model of Jeep.