Supplement to Bulletin 04-01-38-012A Noise Heard When A/C is On - keywords AC air conditioning core evaporator flow hum HVAC pipe refrigerant valve whistle

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Supplement to bulletin 04-01-38-012A, Whistle/Hiss/Hum/Ring Noise Heard When A/C is on. The condition is a result of refrigerant flow through the evaporator and does not adversely affect cooling system performance. If the customer requests a remedy for the noise a new design evaporator will be available in September 2005. The repair kit referenced in bulletin 04-01-38-012A is no longer available and the repair kit installation will be superseded by replacing only the evaporator and AC tube with newly designed parts. The service part kit listed in bulletin 04-01-38-012A will supersede with 2 new part numbers. These new part numbers consist of an Evaporator Core 89018834 and an AC Tube 89024923. These two parts will be the only parts necessary to satisfy the customer complaint and the parts will be available from SPO in September 2005.

Complete bulletin 04-01-38-012A by ordering and replacing the part numbers listed below. Reference eSI for each component to obtain the correct repair procedure. Refer to eSI document 1030055 to replace the Evaporator Core and eSI document 1029979 to replace the AC Tube. Use the labor operation listed in bulletin 04-01-38-012A. Bulletin 04-01-38-012A will be revised to address the new service procedure and part numbers. Until parts are available from SPO, it will be necessary to generate a SPAC case.

Note: When installing the new AC tube part number 89024923, the tube will leave the evaporator core, route along the right frame rail, turn left in front of the condenser and attach to the receiver dryer. The original pipe that routed along the left side of the engine compartment and the small extension pipe that attached to the received dryer are both to be eliminated. Please inspect a 2006 Colorado or Canyon to clarify the new AC tube routing; all 2006 vehicles were manufactured with this change.

Additional PI's related to A/C:

Poor AC Performance - Evap Temp Sensor PIT3626A (Aug 5, 2005)

Blower Motor Inop in any one or more speeds - PIT3688 (Aug 11, 2005)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.