MTC

B1056-REAR BLEND DOOR TRAVEL RANGE TOO SMALL (MTC)

For a complete wiring diagram REFER to DIAGRAMS/ELECTRICAL .

Theory of Operation


The A/C Heater Control calibrates each actuator individually. Automatic calibration occurs upon power up after installing a new A/C Heater Control. Manual calibration occurs by sending a command with the scan tool. The purpose of actuator calibration is to determine the total span of door travel between physical stops. To calibrate the actuator, the A/C Heater Control first moves the door to its soft stop, and then counts the number of pulses it takes to move the door to its other stop. An expected range of span is stored in the control's memory. If the measured calibration value is less than the expected range for this actuator, this DTC will set. Note that the control clears all stored calibration faults at the beginning of the calibration procedure.


- When Monitored:
During actuator calibration.

- Set Condition:
If the total span of the Rear Blend Door is less than the low range limit.






Diagnostic Test


1. CHECK FOR ACTIVE CONTROL CIRCUIT/PERFORMANCE & CONTROL CIRCUIT OPEN DTCs
Turn the ignition on.
With the scan tool, read active HVAC DTCs.
Does the scan tool display any active CONTROL CIRCUIT/PERFORMANCE or CONTROL CIRCUIT OPEN DTCs?

Yes (MTC)


- Diagnose and repair the DTC(s).


No


- Go To 2.


2. INSPECT ACTUATOR & HOUSING ASSEMBLY FOR A CONDITION CAUSING THE DOOR TO SEIZE OR BIND
Turn the ignition off.
Inspect the actuator and the housing assembly for a condition causing the door to seize or bind.
Are there any physical or mechanical problems with the door, housing, or actuator?

Yes


- Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.


No


- Go To 3.


3. CHECK REAR BLEND DOOR TRAVEL
Remove the Rear Blend Door Actuator from the Rear A/C Heater Housing Assembly.
By hand, attempt to rotate the door in both directions. The door should operate smoothly in both directions over approximately 70 degrees of travel.
Does the door operate smoothly in both directions over approximately 70 degrees of travel?

Yes


- Replace the Rear Blend Door Actuator. Then, Go To 4.


No


- Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.


4. RUN THE ACTUATOR CALIBRATION TEST
Turn the ignition on.
With the scan tool, select System Tests and then select Actuator Calibration Test. When the test is complete, select View DTCs.
Does the scan tool display this DTC as active?

Yes


- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test


No


- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.