Silverado 3500 4WD V8-6.6L DSL Turbo VIN 2 (2004)
Accumulator HVAC: Customer Interest
A/C - Doesn't Blow Cold Enough
Bulletin No.: 02-01-38-007C
Date: July 27, 2004
TECHNICAL
Subject:
Poor A/C Performance - A/C Will Not Blow Cold Enough (Perform A/C System Checks, Replace Accumulator if Necessary)
Models:
2002-2004 Chevrolet Silverado
2002-2004 GMC Sierra
with 6.6L Diesel Engine (VINs 1, 2 - RPOs LB7, LLY)
and Denso A/C Compressor
Supercede:
This bulletin is being revised to add part numbers for the hose, bracket and insulator to the Parts Information. Please discard Corporate Bulletin Number
02-01-38-007B (Section 01 - HVAC).
Condition
Some customers may comment on less than desirable A/C performance, especially when the ambient temperature is above 32°C (90°F).
Correction
Perform the following A/C system checks and replace the accumulator with P/N 89018601, if necessary. This new accumulator requires the accumulator
bracket, the accumulator insulator and the A/C suction hose to be replaced also.
^
Check for A/C system leaks.
^
Check the A/C system for proper refrigerant charge. This requires recovering the refrigerant to determine charge in system. Refer to Refrigerant
Recovery and Recharging in the HVAC sub-section of the Service Manual.
^
If no leaks were found and the A/C system is charged to specification, replace the accumulator using the procedure listed below.
If normal diagnostics do not lead to a correction, then perform the following A/C system checks.
1.
Re-calibrate the actuators.
2.
Inspect the lower A/C condenser deflector for proper installation. The deflector should be positioned at the lower part of the condenser and extend
forward into the top of the front bumper and below the two fresh air intake holes.
3.
Check the engine cooling fan clutch for proper operation.
4.
If the vehicle is equipped with a front license plate, inspect for proper installation. If the license plate bracket is installed upside down, it will block
part of the two fresh air intake holes in the bumper. When the license plate bracket is installed correctly, the writing on the back of the bracket will
be upside down.
Inspect for material between the radiator and condenser. Remove the top plate to confirm that there is no restriction. A radiator front filled with
material will decrease condenser performance.
5.
Some improvements have been found by lowering the A/C charge from 0.82 kg (1.8 lbs) to 0.73 kg (1.6 lbs).
6.
Check the low pressure cycling switch for proper operation. The low pressure switch opens at 172-234 kPa (25-34 psi) which stops compressor
operation and closes when the low side pressure reaches 276-310 kPa (40-45 psi). This enables the compressor to turn back on.
Important:
Compressor clutch engagement cannot be used to determine the status of the low pressure switch. The low pressure switch is one of several
inputs to the HVAC control module for A/C request authorization. A/C request is one of several inputs to the powertrain control module
(PCM) that control A/C compressor clutch engagement.
Using a scan tool to monitor low pressure switch status while monitoring the low side pressure with the ACR 2000 at the service port and watch
