Bulletin No.:

Service Bulletin

Date:

19-NA-177
September, 2019

INFORMATION
Subject:

Lack of A/C Performance, Evaporator Freeze Up

This bulletin replaces PIT5625B. Please discard
PIT5625B
Brand:

Model:

Chevrolet
GMC

Model Year:

VIN:

from

to

Colorado

2017

2020

Canyon

2017

2020

Involved Region or Country

from

Engine:

Transmission:

All

All

to

North America, N.A. Export Regions

Additional Options (RPOs)
Condition

Some customers may comment on a lack of cold air along with lack of air flow from A/C
vents.

Cause

The cause of the condition may be the A/C system being used on the coldest setting with
the blower on the lowest speed setting. This can happen in climates with a high ambient
temperature, 85 degrees F (29 C) or above and humidity over 80%. Highest affected
regions are around the Gulf of Mexico.
Note: Technicians need to follow the SI A/C Performance diagnostic procedures first
BEFORE any reprogramming is attempted.

Correction

Follow normal A/C performance diagnosis in SI.
If the condition is not corrected, a Service Only calibration change has been released in
TIS2WEB to correct this specific concern.
Note: Because this only could affect a small set of customers and would be region
specific, this will be a unique calibration referenced with this bulletin number. The
original A/C system calibration will still be available in TIS2WEB.

Service Procedure
Note: Use of this calibration should be accompanied
with an explanation that an increase in the temperature
cycling of the system will be noted. The air output at the
vents will vary by a couple degrees up or down, as it
cools the cabin and is most notable when the outside
temperature and the set point of the system are similar.
Reprogram the H33 HVAC control module, with the
calibration available on TIS2WEB with the SPS
description:
“Refer to TSB #19-NA-177 – Special Use Only. To
reduce evaporator freeze-up in hot, extreme humid
environments, such as gulf coast states. Not to be
used in any other condition or environment due to
some negative effects on cabin comfort.”
Refer to HVAC Control Module Reprogramming with
SPS in SI.

Copyright 2019 General Motors LLC. All Rights Reserved.

Note: 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 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.

Parts Information
No parts are required for this repair.

Page 2

September, 2019

Bulletin No.: 19-NA-177

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

*2886418

HVAC Control Module Reprogramming with SPS for Colorado
and Canyon

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

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

2

Modified

Released August 15, 2019
Revised August 29, 2019 – Added 2020 Model Year

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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