Unable to Read HVAC DTCs Until Bulletin 05-01-38-014 is Completed - keywords accessory communication control head performance tech2

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Engineering has identified an anomaly within the HVAC control head on some 2005-06 crossover sports vans built after January, 2005. A routine diagnostic probe may or may not identify a DTC until the HVAC control head has been reflash per bulletin 05-01-38-014 (Update HVAC Control Module Software) is completed. Engineering is currently working on a new software to address this deviation of the expected behavior. Until such time, technicians should perform 05-01-38-014 prior to performing repairs to the HVAC system.

Example: The owner goes to a dealership for the rear HVAC inop (disconnected actuator); the Technician verifies the concern and runs a diagnostic probe with the Tech 2 to find there are no current/history DTCs. In theory the disconnected actuator should have set one of several different DTCs. Now there are 2 options:

1. Service bulletin 05-01-38-014 (Update HVAC Control Module Software) is completed and the DTC for the actuator appears but the control head will not re-calibrate, so the AC led keep flashing. The Technician repairs the actuator and retests the system.
2. Since there are no DTCs the Technician will check for any objects blocking the temp door, damaged wires, etc. and notice that the actuator is not connected. After re-connecting the actuator the system will work as designed but the control head may not get the updated software.

Note: Service bulletin 05-01-38-014 should be completed prior to performing any diagnostic and/or repairs.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.