Affected vehicles: 2006-’08 Endeavor built between May 16, 2006 and early February 2008 with manual A/C.
Customers of some affected vehicles may complain about one or both of the following conditions:
1. Air flow from the HVAC air vents may randomly change direction and/or the temperature may briefly cycle from hot to cold, and then hot again. This condition is caused by the HVAC controller supplying an incorrect signal and will occur only when the exterior vehicle lighting is on and the instrument panel lighting is set to 70-80% illumination.
2. The direction of air flow may be stuck in one position. Changing the position of the mode dial has no effect on the air flow direction.
Repair Procedure:
Symptom #1: The direction of air flow or the temperature from the vents changes randomly.
1. Replace the heater controller assembly (P/N 7820A271HA).
2. Refer to Section 55 – Heater, Ventilation & Air Conditioning – and remove the mode selection motor. Inspect the mode door shaft on the heater case.
a. If the mode door shaft is not cracked, reinstall the motor according to the service manual.
3. If the mode door shaft is cracked, install a hose clamp around the shaft (see Fig. 1). Position the clamp to avoid contact with the case or motor housing when the shaft rotates. Tighten the clamp firmly around the shaft. Reinstall the motor according to the service manual. 
Note: If parts must be ordered to complete repairs, instruct the customer to keep the Instrument Panel illumination level at 100% bright until repairs are completed.
Symptom #2: The direction of air flow sticks in one position.
1. Replace the heater controller assembly (P/N 7820A271HA).
2. Inspect the mode door shaft following the instructions in Symptom #1.
a. If the shaft is not cracked and the symptom still exists, diagnose and repair as necessary.
b. If the shaft is cracked, install a hose clamp as instructed in Symptom #1. Re-evaluate air flow. If the symptom still exists, diagnose and repair as necessary.
3. Confirm the air flow direction matches the position of the controls in all positions.
Courtesy of ALLDATA.