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DTC B1249 Test: Blend Door Failure

WARNING: This page is about a different car, the 1999 Lincoln Navigator and 1999 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

  1. Check Actuator Operation To Full Cool Position

    Turn ignition off. Disconnect both EATC module connectors (C280 and C281). Connect jumper wire between EATC module connector Orange wire and connector C280 Red/White wire. Connect second jumper wire between EATC module connector C281 Dark Blue/Light Green wire and connector C280 Black wire. If blend door actuator motor moves clockwise to full cool position, go to next step. If it does not move clockwise, go to step 3)  .

  2. Check Actuator Operation To Full Hot Position

    Connect one jumper wire between EATC module connector C281 Dark Blue/Light Green wire and connector C280 Red/White wire. Connect second jumper wire between EATC module connector C281 Orange wire and connector C280 Black wire. If blend door actuator motor moves counterclockwise to full hot position, go to step 8)  . If blend door actuator motor does not move counterclockwise, go to step 9)  .

  3. Check Dark Blue/Light Green Wire Circuit For Short

    Disconnect electronic blend door actuator connector. With an ohmmeter, measure resistance of Dark Blue/Light Green wire between EATC module connector C281 and ground. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair short to ground in Dark Blue/Light Green wire and retest system.

  4. Check Orange Wire Circuit For Short To Ground

    Measure resistance of Orange wire between EATC module connector C281 and ground. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair short to ground in Orange wire and retest system.

  5. Check Dark Blue/Light Green Wire Circuit For Open

    Measure resistance of Dark Blue/Light Green wire between EATC module connector C281 and electronic blend door connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Dark Blue/Light Green wire and retest system.

  6. Check Orange Wire Circuit For Open

    Measure resistance of Orange wire between EATC connector C281 and electronic blend door actuator connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Orange wire and retest system.

  7. Check Actuator Operation

    Remove electronic blend door actuator. See ELECTRONIC BLEND DOOR ACTUATOR  under REMOVAL & INSTALLATION. With actuator drive shaft disengaged from temperature blend door, connect jumper wires, as in step 1)  , and drive blend door actuator to full cool position. Switch jumper wire connections, as in step 2)  and drive blend door actuator to full hot position. If blend door moves in both directions to full hot and full cool positions, repair temperature blend door for blocked or binding condition. Retest system. If electronic blend door actuator did not move as indicated, replace electronic blend door actuator and retest system.

  8. Check Feedback Potentiometer Total Resistance

    With jumper wires connected as in step 2)  , drive electronic blend door actuator to full hot position. Measure resistance between EATC module connector C280 Light Green/Orange wire and connector C281 White/Yellow wire. If resistance is between 5,000 and 7,000 ohms, go to step 13)  . If resistance is not as specified, go to next step.

  9. Check Light Green/Orange Wire Circuit For Open

    Disconnect electronic blend door actuator connector. Measure resistance of Light Green/Orange wire between EATC module connector C281 wire and electronic blend door actuator connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Light Green/Orange wire and retest system.

  10. Check White/Yellow Wire Circuit For Open

    Measure resistance of White/Yellow wire between EATC connector C281 and electronic blend door actuator. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in White/Yellow wire and retest system.

  11. Check Light Green/Orange Wire Circuit For Short

    Measure resistance of Light Green/Orange wire between EATC module connector C280 wire and ground. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair short to ground in Light Green/Orange wire and retest system.

  12. Check White/Yellow Wire Circuit For Short

    Measure resistance of White/Yellow wire between EATC module connector C281 wire and ground. If resistance is more than 10,000 ohms, replace electronic blend door actuator and retest system. If resistance is less than 10,000 ohms, repair short to ground in White/Yellow wire and retest system.

  13. Check Feedback Potentiometer Low Side Resistance

    Using jumper wires as in step 2)  , drive electronic blend door actuator to full warm position. Measure resistance between EATC module connector C280 Purple wire and connector C281 White/Yellow wire. If resistance is between 250 and 1500 ohms, go to step 16)  . If resistance is not as specified, go to next step.

  14. Check Purple Wire Circuit For Open

    Disconnect electronic blend door actuator connector. Measure resistance of Purple wire between EATC module connector C280 and electronic blend door actuator connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Purple wire and retest system.

  15. Check Purple Wire Circuit For Short

    Measure resistance of Purple wire between EATC connector C280 and ground. If resistance is more than 10,000 ohms, replace electronic blend door actuator. Retest system. If resistance is less than 10,000 ohms, repair short to ground in Purple wire and retest system.

  16. Check Feedback Potentiometer High Side Resistance

    Using jumper wire connections as in step 2)  , drive electronic blend door actuator to full warm position. Measure resistance between EATC connector C280 Light Green/Orange wire and Purple wire. If resistance is between 3500 and 6000 ohms, go to next step. If resistance is not as indicated, replace electronic blend door actuator and retest system.

  17. Check Light Green/Orange Wire Circuit For Short

    Measure resistance of Light Green/Orange wire between EATC connector C280 and ground. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair short to ground in Light Green/Orange wire and retest system.

  18. Check White/Yellow Wire Circuit For Short

    Measure resistance of White/Yellow wire between EATC connector C281 and ground. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair short to ground in White/Yellow wire and retest system.

  19. Check Purple Wire Circuit For Short

    Measure resistance of Purple wire between EATC connector C280 and ground. If resistance is more than 10,000 ohms, replace electronic blend door actuator. Retest system. If resistance is less than 10,000 ohms, repair short to ground in Purple wire and retest system.
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