http://acdelcotechconnect.com/pdf/tsb/tsb_03D-128.pdf
AC Delco put out a fact sheet on this issue with their switch:
[FONT=TimesNewRoman,Bold]BULLETIN: 03D-J-128[/FONT]
[FONT=TimesNewRoman,Bold]LINE: 15[/FONT]
[FONT=Arial,BoldItalic]SERVICE BULLETIN[/FONT]
[FONT=TimesNewRoman,Bold]TO: ALL DISTRIBUTORS AND JOBBERS[/FONT]
[FONT=TimesNewRoman,Bold]DATE: SEPTEMBER 26, 2003[/FONT]
[FONT=TimesNewRoman,Bold]FROM: S. D. CHRISTOPHERSEN, PRODUCT SERVICE & TRAINING[/FONT]
[FONT=TimesNewRoman,Bold]SUBJECT: AIR CONDITIONING (A/C) INOPERATIVE/INTERMITTENT, [/FONT][FONT=TimesNewRoman,Bold]A/C BLOWS WARM AIR (REPLACE A/C LOW PRESSURE [/FONT][FONT=TimesNewRoman,Bold]CYCLING SWITCH)[/FONT]
[FONT=TimesNewRoman,Bold]DESCRIPTION:[/FONT]
Air Conditioning (A/C) Inoperative/Intermittent, A/C Blows Warm Air (Replace
A/C Low Pressure Cycling Switch)
2003 Cadillac Escalade, Escalade EXT, Escalade ESV
2002-2003 Chevrolet TrailBlazer, TrailBlazer EXT
2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2002-2003 GMC Envoy, Envoy XL
2003 GMC Sierra, Yukon, Yukon XL
2002-2003 Oldsmobile Bravada
2003 HUMMER H2
[FONT=TimesNewRoman,Bold]CONDITION:[/FONT]
Some customers may comment that the A/C system is intermittently inoperative or blows warm air.
[FONT=TimesNewRoman,Bold]CAUSE:[/FONT]
An intermittent inoperative (open) A/C low pressure cycling switch may be the cause. This is an intermittent condition, and temperatures may play a critical role if the vehicle is in the failed mode or operating as designed.
[FONT=TimesNewRoman,Bold]CORRECTION:[/FONT]
Follow the diagnosis and service procedure below to correct this condition:
1. Park the vehicle inside or in the shade.
2. Open the windows in order to ventilate the interior of the vehicle.
3. If the A/C system was operating, allow the A/C system to equalize.
4. Turn OFF the ignition.
5. Open the hood and install fender covers.
6. Install the J 43600 ACR 2000 Air Conditioning Service Center or equivalent equipment.
Important:
• The ambient temperature must be at least 16°C (60°F).
• Do not induce additional airflow across the front of the vehicle during the
test.
7. Record the ambient temperature displayed on the J 43600.
Record readings of the low and high side STATIC pressures. The pressures
should be within the specifications listed below.
• Above 16°C (60°F): 345 kPa (50 psi)
• Above 24°C (75°F): 483 kPa (70 psi)
• Above 33°C (90°F): 690 kPa (100 psi)
• If the static pressures are within specification, continue with Step 12.
• If the static pressures are NOT within specifications, refer to Leak Testing
in the appropriate service information.
9. Apply the parking brake.
10. Place the transaxle/transmission in PARK.
11. Start the engine.
12. Turn on the A/C system.
13. Inspect the A/C compressor to see if it is operating properly.
1 – Accumulator
2 – Low Pressure Cycling Switch
14. If the compressor is not operating as designed, tap on the low pressure cycling
switch with a small hand tool. The compressor should start operating
correctly.
15. If the compressor does not operate correctly after tapping on the low pressure
cycling switch, disconnect the switch and jumper the lower pressure cycling
switch connector with a fused jumper. If the compressor still does not operate
properly, refer to HVAC Compressor Clutch Does Not Engage in the
appropriate service information.
Important: DO NOT USE A/C low-pressure cycling switch P/N 15-5715
(1132749) or P/N 15-5720 (15035084) on the vehicles listed above.
If the compressor does operate correctly after tapping on the switch or
jumping the low pressure cycling switch connector, replace the low pressure
cycling switch, P/N 89040362. Refer to Air Conditioning (A/C) Low
Pressure Switch Replacement in the appropriate service information.
17. Perform the Air Conditioning (A/C) System Performance Test in the
appropriate service information.
18. Disconnect the J 43600 ACR 2000 Air Conditioning Service Center or
equivalent equipment.
19. Remove the fender covers and close the hood.
[FONT=TimesNewRoman,Bold]PARTS INFORMATION:
[FONT=TimesNewRoman,Bold]Important
[FONT=TimesNewRoman,Bold]Part Number Description Qty
15-50156 (89040362) Switch, Pressure Cycling 1
Parts are currently available from ACDelco/GMSPO.
Chevy Parts
Chevy Truck Parts
Trailblazer Parts
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