B1055-Rear Blend Door Control Circuit Open: Notes

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS information.

Theory of Operation 

After the initial installation of the A/C Heater Control, the controller is calibrated to each individual blend/mode door actuator. These calibrations are stored as in the number of pulses it takes to move the door from one stop to another. The A/C Heater Control drives the Door Actuators by the use of Door Driver circuit and a Common Door Driver circuit and monitors all door actuator pulses to detect door movement in both directions. Most of the door actuators share a common door driver circuit but each door actuator has its own unique driver circuit. Due to shared circuitry, similar Diagnostic Trouble Codes (DTCs) can set at the same time for multiple actuators depending upon the type of circuit malfunction, its location, and the direction the actuator is moving when the malfunction is present.

• >>When Monitored:<< With the ignition on and when a HVAC Actuator Calibration Test is performed.
• >>Set Condition:<< If an HVAC Actuator Calibration Test is performed the A/C Heater Control detects there are no feedback pulses detected in that direction, the controller commands the actuator in the opposite direction. If no feedback pulses are detected in either direction this DTC will set. If the A/C Heater Control detects a valid pulse feedback in both directions, the DTC will change from Active to Stored and will stay in the controllers memory for 100 ignition cycles.

Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to HVAC .