Bulletin No.:

Service Bulletin

Date:

19-NA-179
August, 2019

TECHNICAL
Subject:

Air Conditioning Blows Cold then Warm, Intermittently

Brand:

Model:

Chevrolet

Express

GMC

Savana

Model Year:

VIN:

from

to

2017

2019

Involved Region or Country

from

Engine:

Transmission:

LWN

All

to

North America, N.A. Export Regions

Additional Options (RPOs)
Condition

Some customers, particularly in hot ambient temperatures, may comment that the air
conditioning changes intermittently, from blowing cold to blowing warm air.

Cause

The cause of the condition may a software anomaly.

Correction

Note: An updated software calibration has been released to reduce compressor off time
cycling.
If all normal AC diagnostics have been completed with no issue found, reprogram the
ECM, following the steps in the Service Procedure below.

Service Procedure
Note: Carefully read and follow the instructions below.
•

•

•

•

Ensure the programming tool is equipped with the
latest software and is securely connected to the
data link connector. If there is an interruption
during programming, programming failure or
control module damage may occur.
Stable battery voltage is critical during
programming. Any fluctuation, spiking, over
voltage or loss of voltage will interrupt
programming. Install a GM Authorized
Programming Support Tool to maintain system
voltage. Refer to www.gmdesolutions.com for
further information. If not available, connect a fully
charged 12 V jumper or booster pack
disconnected from the AC voltage supply. DO
NOT connect a battery charger.
Turn OFF or disable systems that may put a load
on the vehicles battery such as; interior lights,
exterior lights (including daytime running lights),
HVAC, radio, etc.
Clear DTCs after programming is complete.
Clearing powertrain DTCs will set the Inspection/
Maintenance (I/M) system status indicators to NO.

Copyright 2019 General Motors LLC. All Rights Reserved.

Page 2

August, 2019

Bulletin No.: 19-NA-179

5164840

Note: If the Same Calibration/Software Warning is
noted on the SPS Summary screen, record the
warranty claim code (WCC) and select OK and follow
screen instructions. After a successful programming
event, the WCC is located in the Service Programming

System dialogue box of the SPS Summary screen. No
further action is required. Refer to the Warranty section
of the bulletin
1. Reprogram the Engine Control Module. Refer to
K20 Engine Control Module: Programming and
Setup, in SI.

Bulletin No.: 19-NA-179

August, 2019

Page 3

5164843

2. Record SPS Warranty Claim Code on job card for
warranty transaction submission.

Parts Information
No parts are required for this repair.

Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
Labor Operation

Description

Labor Time

2886428*

Engine Control Module Reprogramming with SPS for AC
Repair

0.3 hr

*This is a unique Labor Operation for Bulletin use only.
* To avoid warranty transaction rejections, carefully read and follow the instructions below:
• The SPS Warranty Claim Code must be accurately entered in the “SPS Warranty Claim Code” field of the transaction.
• When more than one Warranty Claim Code is generated for a programming event, it is required to document all Warranty
Claim Codes in the “Correction” field on the job card. Dealers must also enter one of the codes in the “SPS Warranty Claim
Code” field of the transaction, otherwise the transaction will reject. It is best practice to enter the FINAL code provided
by SPS.

Page 4

August, 2019

Bulletin No.: 19-NA-179

Warranty Claim Code Information Retrieval
If the SPS Warranty Claim Code was not recorded on
the Job Card, the code can be retrieved in the SPS
system as follows:
1. Open TIS on the computer used to program the
vehicle.
2. Select and start SPS.
3. Select Settings.
4. Select the Warranty Claim Code tab.
The VIN, Warranty Claim Code and Date/Time will be
listed on a roster of recent programming events. If the
code is retrievable, dealers should resubmit the
transaction making sure to include the code in the SPS
Warranty Claim Code field.
Version

1

Modified

Released August 13, 2019.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

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