Noise When A/C Selected and Rear Fan On (Replace Auxiliary Thermal Expansion Valve)

This bulletin is being revised to add 2001 Chevrolet Trans Sport (Export Europe) to the Model section. Please discard Corporate Bulletin Number 01-01-38-010 (Section 01-HVAC).

Some customers may comment on a noise that occurs when the A/C mode is selected and the rear fan is on. This noise can be described as a:

The noise lasts for about 10-15 seconds when the compressor cycles on and is typically intermittent. This condition may occur at any ambient temperature that permits compressor operation.

This condition may be caused when the A/C compressor is engaged; a pressure hammer in the lines can be heard.

Replace the auxiliary thermal expansion valve (TXV). The new TXV is not equipped with a solenoid. Use the procedure and part number listed below.

1. Recover the refrigerant. Refer to the Refrigerant Recovery and Recharging procedure in the Service Manual.
2. Remove the left lower quarter trim panel. Refer to the Rear Quarter Lower Trim Panel Replacement procedure in the Interior Trim sub-section of the Service Manual.
3. Remove the foam wrap from the auxiliary TXV.



4. Remove the auxiliary TXV line clamp screws.
5. Remove the auxiliary TXV line clamp from the HVAC module assembly.
6. Remove the bolt from the auxiliary TXV line block fitting.
7. Remove the A/C lines from the auxiliary TXV.
8. Cap or tape the A/C lines.
9. Disconnect the auxiliary TXV solenoid electrical connector.



10. Remove the auxiliary TXV to evaporator core bolts.
11. Remove the auxiliary TXV from the evaporator core.
12. Cap or tape the A/C lines.
13. Remove and discard the sealing washers.
14. Remove the cap or tape from the evaporator lines.
15. Using a lint-free clean, dry cloth, carefully clean the sealing surfaces of the evaporator lines.
16. Carefully slide the new sealing washers onto the A/C line until seated.

Important: The new TXV is not equipped with a solenoid, secure harness connector with tape.

17. Install the new auxiliary TXV to the evaporator core.
18. Install the auxiliary TXV to evaporator core mounting bolts.

Tighten
Tighten the bolts to 3.5 N·m(31 lb in).

19. Remove the cap or tape from the A/C lines.
20. Using a lint-free clean, dry cloth, carefully clean the sealing surfaces of the A/C lines.
21. Carefully slide the new sealing washers onto the A/C line until seated.
22. Install the auxiliary TXV line block fitting retaining bolt.

Tighten
Tighten the bolt to 11 N·m(97 lb in).

23. Install the auxiliary TXV line clamp to the HVAC module assembly.
24. Install the auxiliary TXV line clamp screws.

Tighten
Tighten the screws to 1.6 N·m(14 lb in).

25. Install the new foam wrap to the auxiliary TXV.
26. Evacuate and recharge the A/C system. Refer to the Refrigerant Recovery and Recharging procedure in the Service Manual.
27. Leak test the fittings using J 39400-A.
28. Install the left lower quarter trim panel. Refer to the Rear Quarter Lower Trim Panel Replacement procedure in the Interior Trim sub-section of the Service Manual.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: