Except for the selection of the recirculation door, the vaccum controls should be exactly the same in MAX A/C as for VENT.
If the airflow selection is correct for VENT, then the EATC is likely bad.
Try running the EATC Self-Test as follows from the service CD"
l The self-test can be initiated at any time. Normal operation of the system stops when the self-test is activated.
l To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTOMATIC button within two seconds. The display will show a pulse tracer going around the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.
l If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.
l If a condition exists but no DTCs appear during the self-test, refer to the Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Improper Operation.
l To exit self-test and retain all intermittent DTCs, push the blue (cooler temperature) button. The control will exit self-test, retain all intermittent DTCs and then turn OFF (display blank).
l To exit self-test and clear all DTCs, press the DEFROST button. The vacuum fluorescent display window will show 888 and all function symbols for one second. Then, the EATC control assembly will turn OFF (display blank) and all DTCs will be cleared.
l Always exit the self-test before powering the system down (system turned OFF).
l Intermittent DTCs will be deleted after 80 ignition switch ON cycles after the intermittent condition occurs.
Let us know what the results are..