How do you read the fault codes of a Jeep Grand Cherokee Limited with the dual control system?

Answer 1

If you have a Jeep Grand Cherokee with the Automatic Zone Control system (AZC) (dual controls). Follow the steps below to read the AZC fault codes.

1. Turn on the ignition switch.

2. Turn on the AZC system. The temperature settings should be displayed for both sides.

3. Simultaneously hold down the AC and the Re-Circ buttons.

4. Then at the same time, turn the driver's side temperature (Left) control knob to the right (CW) one click.

5. The code numbers will display one at a time with a short delay in between.

21 or 53 - Left temperature door travel to small.

22 or 54 - Left temperature door travel to large.

23 or 55 - Right temperature door travel to small.

24 or 56 - Right temperature door travel to large.

All of the above codes indicate a blend door problem.

The lower number codes are current codes and the larger number is an historic code. The most common readout is 52,54,56.

52 is a re-circ door code. The re-circ door regulates whether the air coming into the system is external air or internal air. This door suffers from the same design flaw as the blend doors and you need to make sure that you don't have problems or just the blend door fix won't help.

54 is the most common code indicating a broken driver's side blend door. The door is on a horizontal axis and when it breaks, it typically falls to the bottom of the box, blocking the heater core, giving no heat and lower efficiency AC. 56 indicates the same issue on the passenger side. Usually the passenger side will fail first, followed shortly by the driver's side. HeaterTreater has kits to address both the blend doors and the re-circ door. The blend door kit provides metal doors and is installed through the glove box with no disassembly of the dash required. The doors are adjustable during installation, insuring a perfect fit and 100% efficient operation.

To read the fault codes:

1. Turn on the ignition switch.

2. Turn on the AZC system. The temperature settings should be displayed for both sides.

3. Simultaneously hold down the AC and the Re-Circ buttons.

4. Then turn the driver's side temperature (Left) control knob to the right (CW) one click.

5. Release the AC and Re-circ buttons.

If there are no fault codes, the "00" display value will remain in the window.

If there are any codes, each will be displayed for one second in ascending numerical sequence (note: no effort is made to display faults in the order they occurred). The left side set temperature display will be blanked and the right side set temperature display will indicate current and historical codes (8 historical max) presently active.

Once all codes have been displayed, the system will repeat the fault code numbers. This will continue until the left side set temperature control is moved at least one detent position in either direction, by pressing both the A/C and Recirc buttons at the same time, or the ignition is turned off.