File in Section:

Service Bulletin

01 - HVAC

Bulletin No.:

11-01-39-005A

Date:

February, 2013

TECHNICAL
Subject:

Reduced Heater Performance with Winter Grille Cover Installed

Models:

2007-2013 Chevrolet Silverado 2500/3500 Series
2007-2013 GMC Sierra 2500/3500 Series
Equipped with Duramax™ Diesel Engine (RPO LMM, LML or LGH) Combined with
RPOs CJ2 and V10

This bulletin is being revised to add the 2013 model year. Please discard Corporate Bulletin
Number 11-01-39-005 (Section 01 – HVAC).

Condition
Some customers may comment on reduced heater
performance or the need to increase the climate control
temperature settings when using the winter grille cover
(Cover, 1-piece, covers radiator grille for diesel engines
in winter weather).

Use the following steps to relocate the ambient air
temperature sensor into the lower bumper opening
using a remote mounting bracket.
1. Remove the radiator air upper baffle/deflector.
Refer to Radiator Air Upper Baffle and Deflector
Replacement in SI.

Cause
The winter grille cover restricts airflow, allowing the
underhood temperatures to increase. This provides an
elevated temperature signal to the HVAC system. This
may cause the automatic temperature control to reduce
the amount of heat being delivered to the passenger
compartment.

Correction #1 for Model Year 2011-2013
Vehicles
Relocating the ambient air temperature sensor will
allow the sensor to continue detecting cooler air.

2736238

2. Carefully remove the ambient air sensor from the
radiator support.

Copyright 2013 General Motors LLC. All Rights Reserved.

Page 2

February, 2013

2736239

3. Remove the wire retainer closest to the sensor.

Bulletin No.: 11-01-39-005A

2736243

5. Locate the right vertical support section of the core
support lower cross member.

2736241

4. Relocate the sensor and sensor harness in front of
the transmission oil cooler as shown.

2736244

6. Mark the center of the vertical support with a paint
pen as shown and center punch the mark at the
drill location.
7. Drill a 3 mm (1/8 in) hole. Use care to not damage
the transmission oil cooler or the radiator.
8. Coat the hole with GM Synthetic Lubricant With
Teflon®, P/N 12371287 (in Canada, use
10953437), to prevent corrosion.

Bulletin No.: 11-01-39-005A

February, 2013

2736245

9. Using a large flange, 1/8 in. shank rivet, such as
*Kent Industries part #P57356 or the equivalent,
rivet the service bracket to the cross member as
shown.

Page 3

2736247

• If the sensor is loose in the bracket, install a
push tight retainer such as *Kent Industries part
#P42999 or the equivalent as shown.
11. Reinstall the radiator air upper baffle/deflector.
Refer to Radiator Air Upper Baffle and Deflector
Replacement in SI.
*We believe this source and their products to be
reliable. There may be additional manufacturers of
such products/materials. General Motors does not
endorse, indicate any preference for or assume any
responsibility for the products or material from this firm
or for any such items that may be available from other
sources.

Correction #2 for Model Year 2007-2010
Vehicles

2736246

10. Install the temperature sensor into the bracket as
shown.
• If the retention fins on the sensor mounting pin
were damaged when removing the sensor, the
sensor may be loose in the bracket.

For vehicles equipped with Automatic Temperature
Control HVAC (RPO CJ2), the ambient (outside) air
temperature sensor needs to be relocated.
Use the following steps to relocate the ambient
(outside) air temperature sensor.
1. Remove the radiator grille. Refer to the Radiator
Grille Replacement procedure in SI.
2. Remove the ambient air sensor from its current
location by carefully lifting the sensor from the
radiator support cross bar.
3. Remove the harness clip nearest to the sensor.

Page 4

February, 2013

Bulletin No.: 11-01-39-005A

Parts Information
*Contact Kent Automotive at 1-888-YES-KENT or
online at www.kent-automotive.com.
Part Number

Description

12371287 (in
Canada, use
10953437)

GM SYNTHETIC LUBRICANT WITH
TEFLON®

22743319

BRACKET, AMB AIR TEMP SEN

P42999*

RETAINER, PUSH-TITE M6 STUD

P57356*

SUPER-GRIP BLIND RIVET, LARGE
FLANGE 1/8 DIA. X 5/16L

Warranty Information
For vehicles repaired under warranty, use:

2559256

4. Reinstall the ambient air sensor to the new location
using the existing hole (1) in the lower section of
the radiator support.

Labor
Operation

Description

Labor
Time

D9781*

Relocate Ambient (Outside) Air
Temperature Sensor

0.6 hr

*This is a unique labor operation for bulletin use only. It will
not be published in the Labor Time Guide.

2559257

5. Reinstall the harness clip to the existing hole (2) in
the radiator support.
6. Reinstall the radiator grille. Refer to the Radiator
Grille Replacement procedure in SI.

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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