PC Board Replacement

! Before performing this repair, obtain a grounded anti-static mat. Place the control unit on the mat and attach wrist band.

1. Remove six Torx(R) (T-10) screws from metal base.

2. Place control unit on an anti-static mat with control unit face towards you.

3. Put anti-static bracelet on your wrist and ground bracelet to anti static work station.

4. Pry apart two plastic retainers from metal base and remove metal base.

CAUTION:
Do not touch any metallic pins or surfaces on PC board. Handle the PC board by its edges.

5. Carefully remove PC board from control unit. Push on the plastic parts of the harness connectors if necessary.

6. Holding the PC board by its edges, remove ribbon plug from PC board and scrap old PC board.

CAUTION:
Do not touch any metallic pins or surfaces on PC board. Handle the PC board by its edges.

7. Remove new PC board from its packaging.

8. Ensure ribbon cable is not twisted. Carefully install ribbon plug fully and firmly onto new PC board.

9. Holding the PC board by its edges, tilt control unit horizontally and carefully install new PC board.

NOTE:
Ensure that both the black and the white connector will fit into control unit housing.

CAUTION:
Screws must not be over-tightened or allowed to drop into control unit interior. If a screw falls into control unit interior, the unit must be scrapped.

10. Position metal cover and using magnetic screwdriver, snugly tighten six retaining screws.

11. Install label provided with STC3702K on control unit over old label to denote service update.

12. Install four multi-connectors onto control unit, making sure that the plugs are fully seated in sockets.

13. Place control unit into dash and secure with four screws.

14. Install center console side panels and secure with screws removed earlier.

NOTE:
A complete test of the newly installed control unit must now be performed.

15. First, place ignition switch in position 2:.
Front panel must show:

^ Temp. = 21°C (70°F) and 21°C (70°F).
^ Face vent LED illuminated.

16. Complete HVAC initialization procedure using TestBook.

17. After initialization is completed with TestBook, start the engine and set temp to LO/LO.

18. Observe that the following HVAC functions occur:

^ Blower speed to MAX
^ Recirc. to ON
^ A/C ON

NOTE:
After 10 secs. cold air should be emitted from the vents. Make sure that the air is circulated using the recirculation mode, not fresh air.

19. Next, with the engine running set the temperature to HI/HI.

20. Observe that the following HVAC functions occur:

^ Blower slows to MEDIUM
^ Recirc. to OFF
^ A/C is ON

NOTE:
After 10 seconds hot air should be emitted from the vents. Make sure that the air is circulated using the recirculation mode, not fresh air.

21. Set distribution to the following positions and verify at each step the LED is illuminated above the appropriate button and the air comes out of the appropriate vent.

^ Face and feet.
^ Then to just feet.
^ Then to windshield and feet.
^ Then to just windshield.

22. Push each heated seat buttons and check that the LED is illuminated above the appropriate button and the seat begins to heat up.

23. Push both demist buttons (front and back) and check that the LED is illuminated above the appropriate button and the relay is heard switching.

24. Connect TestBook and interrogate HVAC system to determine if any faults are stored. Ensure that cold climate package is selected for vehicle specifications.

NOTE:
The HVAC control unit logic includes a self-tune feature to ensure optimum air control flap position, both on assembly and during the early life bedding in period. The self-tune routine. is activated on the 1st, 10th, 20th, 50th, 100th, 500th and subsequent 500th start-ups. It sweeps the air control flaps (recirculation, blend, and distribution) through all positions, and takes 90 seconds to complete. During this time, there is no fan operation or airflow.

! After servicing a vehicle that requires a new control unit, inform the customer of the self-tuning routine. This will ensure that the customer does not mistake the self-tuning as a fault. Explain to the customer that the self-tuning routine is a calibration process that improves the performance consistency throughout the life of the vehicle and is done to accommodate any wear of the mechanisms associated with the HVAC unit.