Mode Door Stall/Feedback Failure Trouble Code
CODE #24NAME OF CODE
Mode Door Feedback Failure
Blend Door Feedback Failure
WHEN MONITORED
Continuously
SET CONDITION
BCM detects a loss of signal on the mode feedback and/or blend feedback inputs
THEORY OF OPERATION
At the first ignition on after a battery disconnect, and upon request from the DRB III, Manual HVAC head, or ATC head, the BCM will run each of the three HVAC actuators (mode, blend and recirc) from end-to-end to learn their limits of travel. The mode door and the blend door each have a feedback signal, which is pulled up through the BCM to 5V, which allows the BCM to know the position of both doors so it can control them appropriately. It either of those signals is out of the calibrated range by more than 48mV, or if the minimum amount of travel between the endpoints is not seen during calibration, the appropriate fault will be set.
PROBABLE CAUSES
- Wiring open circuit
- Wiring Short to ground
- Wiring short to battery
- Failed HVAC actuator
- Failed BCM
CODE #33
NAME OF CODE
Mode Door Stall Test Failure
Blend Door Stall Test Failure
Recirculation Door Test Failure
WHEN MONITORED
During HVAC motor calibration
SET CONDITION
BCM is unable to detect the end of travel for one or more of the HVAC doors
THEORY OF OPERATION
At the first ignition on after a battery disconnect, and upon request from the DRB III, Manual HVAC head, or ATC head, the BCM will run each of the three HVAC actuators (mode, blend, and recirc) from end-to-end to learn their limits of travel. If the BCM has activated the mode door for 13 seconds, the blend door for 7.8 seconds, or the recirc door for 6 seconds and has still not detected the end of travel (by detecting the increased stall current), The appropriate fault will be set.
PROBABLE CAUSES
- Wiring open circuit
- Failed HVAC actuator
- Failed BCM