2023 GMC SIERRA air condition

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Introduction 3
A circle with a slash through it is a safety
symbol which means“Do not,” “Do not do
this,” or“Do not let this happen.”
Symbols
The vehicle has components and labels that
use symbols instead of text. Symbols are
shown along with the text describing the
operation or information relating to a
specific component, control, message, gauge,
or indicator.
M:Shown when the owner’s manual has
additional instructions or information.
*: Shown when the service manual has
additional instructions or information.
0: Shown when there is more information
on another page — “see page.” Vehicle Symbol Chart
Here are some additional symbols that may
be found on the vehicle and what they
mean. See the features in this manual for
information.
u:
Air Conditioning System
G:Air Conditioning Refrigerant Oil
9:Airbag Readiness Light
!:Antilock Brake System (ABS)
$:Brake System Warning Light
9:Dispose of Used Components Properly
P:Do Not Apply High Pressure Water
B:Engine Coolant Temperature
_:Flame/Fire Prohibited
H: Flammable
[:Forward Collision Alert
R:Fuse Block Cover Lock Location
+:Fuses
j:ISOFIX/LATCH System Child Restraints
Q:Keep Fuse Block Covers Properly
Installed
|: Lane Change Alert
@:Lane Departure Warning
A:Lane Keep Assist
*: Malfunction Indicator Lamp
::Oil Pressure
X:Park Assist
~:Pedestrian Ahead Indicator
O:Power
7:Rear Cross Traffic Alert
I:Registered Technician
/:Remote Vehicle Start
h:Risk of Electrical Fire

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Keys, Doors, and Windows 47
Roof
Sunroof
1. SLIDE Switch
2. TILT Switch
If equipped, the sunroof operates when the
ignition is on or in ACC/ACCESSORY, or when
Retained Accessory Power (RAP) is active.
SeeRetained Accessory Power (RAP) 0227. Slide Switch
Express-Open/Express-Close :
To
express-open the sunroof, fully press and
release
I(1). Press and releaseI(1) again
to stop the movement. To express-close the
sunroof, fully press and release
K(1).
Press and release
K(1) again to stop the
movement.
Sunroof Comfort Stop Position : This vehicle
may be equipped with a comfort stop to
prevent excessive wind noise. The sunroof
will stop approximately halfway open during
an express open. To fully open the sunroof,
press and release
I(1) again.
Open/Close (Manual Mode) : To open the
sunroof, press and hold
I(1). ReleaseI(1)
to stop the movement. Press and hold
K
(1) to close the sunroof. ReleaseK(1) to
stop the movement. Tilt Switch
Vent :
From the closed position, press
J(2)
to vent the sunroof. Press
K(2) to close
the vent.
When the sunroof is opened, an air deflector
will automatically raise. The air deflector will
retract when the sunroof is closed.
The sunroof also has a sunshade, which can
be pulled forward to block sun rays. The
sunshade must be opened and closed
manually.
Automatic Reversal System
The sunroof has an automatic reversal
system that is only active when the sunroof
is operated in express-close mode.
If an object is in the path while
express-closing, the reversal system will
detect an object, stop, and open the sunroof
slightly.
If frost or other conditions prevent closing,
override the feature by closing the sunroof
in manual mode. To stop movement, release
K(1).

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
70 Seats and Restraints
off using the controls for those features.
If any of these systems are damaged in the
crash they may not operate as normal.
{Warning
A crash severe enough to inflate the
airbags may have also damaged
important functions in the vehicle, such
as the fuel system, brake and steering
systems, etc. Even if the vehicle appears
to be drivable after a moderate crash,
there may be concealed damage that
could make it difficult to safely operate
the vehicle.
Use caution if you should attempt to
restart the engine after a crash has
occurred.
In many crashes severe enough to inflate
the airbag, windshields are broken by
vehicle deformation. Additional windshield
breakage may also occur from the front
outboard passenger airbag.
.Airbags are designed to inflate only once.
After an airbag inflates, you will need
some new parts for the airbag system.
If you do not get them, the airbag
system will not be there to help protect
you in another crash. A new system will include airbag modules and possibly other
parts. The service manual for the vehicle
covers the need to replace other parts.
.The vehicle has a crash sensing and
diagnostic module which records
information after a crash. See
Vehicle
Data Recording and Privacy 0405 and
Event Data Recorders 0406.
.Let only qualified technicians work on the
airbag systems. Improper service can
mean that an airbag system will not work
properly. See your dealer for service.
Passenger Sensing System
The vehicle has a passenger sensing system
for the front outboard passenger position.
The passenger airbag status indicator will
light on the overhead console when the
vehicle is started.
United States
Canada
The words ON and OFF, or the symbols for
on and off, will be visible during the system
check. When the system check is complete,
either the word ON or OFF, or the symbol
for on or off, will be visible. See Passenger
Airbag Status Indicator 0119.
The passenger sensing system turns off the
front outboard passenger frontal airbag
under certain conditions. No other airbag is
affected by the passenger sensing system.
The passenger sensing system works with
sensors that are part of the front outboard
passenger seat and seat belt. The sensors
are designed to detect the presence of a
properly seated occupant and determine if
the front outboard passenger frontal airbag
should be allowed to inflate or not.
According to accident statistics, children are
safer when properly secured in a rear seat
in the correct child restraint for their weight
and size.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
74 Seats and Restraints
{Warning
For up to 10 seconds after the vehicle is
turned off and the battery is
disconnected, an airbag can still inflate
during improper service. You can be
injured if you are close to an airbag
when it inflates. Avoid yellow connectors.
They are probably part of the airbag
system. Be sure to follow proper service
procedures, and make sure the person
performing work for you is qualified to
do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the vehicle's
frame, bumper system, height, front end,
or side sheet metal, may keep the airbag
system from working properly.
The operation of the airbag system can also
be affected by changing, including
improperly repairing or replacing, any parts
of the following:
.Airbag system, including airbag modules,
front or side impact sensors, sensing and
diagnostic module, or airbag wiring
.Front seats, including stitching, seams,
or zippers
.Seat belts
.Steering wheel, instrument panel,
overhead console, ceiling trim, or pillar
garnish trim
.Inner door seals, including speakers
Your dealer and the service manual have
information about the location of the airbag
modules and sensors, sensing and diagnostic
module, and airbag wiring along with the
proper replacement procedures.
In addition, the vehicle has a passenger
sensing system for the front outboard
passenger position, which includes sensors
that are part of the passenger seat. The
passenger sensing system may not operate
properly if the original seat trim is replaced
with non-GM covers, upholstery, or trim; or
with GM covers, upholstery, or trim
designed for a different vehicle. Any object,
such as an aftermarket seat heater or a
comfort-enhancing pad or device, installed
under or on top of the seat fabric, could
also interfere with the operation of the
passenger sensing system. This could either
prevent proper deployment of the passenger
airbag(s) or prevent the passenger sensing system from properly turning off the
passenger airbag(s). See
Passenger Sensing
System 070.
If the vehicle has rollover roof-rail airbags,
see Different Size Tires and Wheels 0353 for
additional important information.
If a snow plow is added to the vehicle, the
airbags should still work properly. The
airbag systems were designed to work
properly under a wide range of conditions,
including snow plowing with vehicles that
have the optional snow plow prep package
(RPO VYU). Do not change or defeat the
snow plow's “tripping mechanism.” If you
do, it can damage the snow plow and the
vehicle, and may cause an airbag
deployment.
If the vehicle must be modified because you
have a disability and have questions about
whether the modifications will affect the
vehicle's airbag system, or if you have
questions about whether the airbag system
will be affected if the vehicle is modified for
any other reason, call Customer Assistance.
See Customer Assistance Offices 0398.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
96 Seats and Restraints
tether. SeeLower Anchors and Tethers
for Children (LATCH System) 082 for
more information on using the top
tether anchors.
7. Before placing a child in the child restraint, make sure it is securely held in
place. To check, grasp the child restraint
at the seat belt path and attempt to
move it side to side and back and forth.
When the child restraint is properly
installed, there should be no more than
2.5 cm (1 in) of movement.
To remove the child restraint, unbuckle the
vehicle seat belt and let it return to the
stowed position. If the top tether is attached
to a top tether anchor, disconnect it.
For outboard rear seating positions, if the
child restraint cannot be installed properly
with the head restraint in place, the head
restraint may be removed. See your dealer
for assistance with removal, and store the
removed head restraint in a secure place.
When the child restraint is removed,
reinstall the head restraint before the
seating position is used. For reinstallation
instructions, see “Head Restraint or Headrest
Removal and Reinstallation” underLower
Anchors and Tethers for Children (LATCH
System) 082.Securing Child Restraints (With
the Seat Belt in the Front
Passenger Seat)
This vehicle has airbags. A rear seat is a
safer place to secure a forward-facing child
restraint. See Where to Put the Restraint
0 80.
In addition, the vehicle has a passenger
sensing system which is designed to turn off
the front outboard passenger frontal airbag
under certain conditions. See Passenger
Sensing System 070 and
Passenger Airbag Status Indicator 0119 for
more information, including important
safety information.
Never put a rear-facing child restraint in the
front. This is because the risk to the
rear-facing child is so great, if the airbag
deploys.
{Warning
A child in a rear-facing child restraint can
be seriously injured or killed if the front
outboard passenger frontal airbag
inflates. This is because the back of the
rear-facing child restraint would be very
(Continued)
Warning (Continued)
close to the inflating airbag. A child in a
forward-facing child restraint can be
seriously injured or killed if the front
outboard passenger frontal airbag inflates
and the passenger seat is in a forward
position.
Even if the passenger sensing system has
turned off the front outboard passenger
frontal airbag, no system is fail-safe. No
one can guarantee that an airbag will not
deploy under some unusual circumstance,
even though it is turned off.
Secure rear-facing child restraints in a
rear seat, even if the airbag is off. If you
secure a forward-facing child restraint in
the front outboard passenger seat,
always move the seat as far back as it
will go. It is better to secure the child
restraint in a rear seat.
SeePassenger Sensing System 070 for
additional information.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Instruments and Controls 117
indicates oil pressure outside the normal
operating range, check the engine oil as
soon as possible.
SeeEngine Oil 0306.
Caution
Lack of proper engine oil maintenance
can damage the engine. Driving with the
engine oil low can also damage the
engine. The repairs would not be covered
by the vehicle warranty. Check the oil
level as soon as possible. Add oil if
required, but if the oil level is within the
operating range and the oil pressure is
still low, have the vehicle serviced.
Always follow the maintenance schedule
for changing engine oil.
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
Engine Coolant Temperature
Gauge
Metric Uplevel Shown, Midlevel and Base Level Similar
English Uplevel Shown, Midlevel and Base Level Similar
This gauge measures the temperature of the
vehicle's engine coolant.
While driving under normal operating
conditions, if the needle moves into the red
warning area, the engine is too hot. Pull off
the road, shift to P (Park) or N (Neutral) and
let the engine idle.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
118 Instruments and Controls
Voltmeter Gauge
Uplevel Shown, Base Level and MidlevelSimilar
When the ignition is on, this gauge indicates
the battery voltage.
When the engine is running, this gauge
shows the condition of the charging system.
The gauge can transition from a higher to
lower or a lower to higher reading. This is
normal. If the vehicle is operating outside
the normal operating range, the charging
system light comes on. See Charging System
Light 0120. The voltmeter gauge may also
read lower when in fuel economy mode.
This is normal. Readings outside the normal operating
range can also occur when a large number
of electrical accessories are operating in the
vehicle and the engine is left idling for an
extended period. This condition is normal
since the charging system is not able to
provide full power at engine idle. As engine
speeds are increased, this condition should
correct itself as higher engine speeds allow
the charging system to create maximum
power.
The vehicle can only be driven for a short
time with the readings outside the normal
operating range. If the vehicle must be
driven, turn off all accessories, such as the
radio and air conditioner.
Readings outside the normal operating
range indicate a possible problem in the
electrical system. Have the vehicle serviced
as soon as possible.
Seat Belt Reminders
Driver Seat Belt Reminder Light
There is a driver seat belt reminder light on
the instrument cluster.
When the vehicle is started, this light
flashes and a chime may come on to remind
the driver to fasten their seat belt.
Then the light stays on solid until the belt is
buckled. This cycle may continue several
times if the driver remains or becomes
unbuckled while the vehicle is moving.
If the driver seat belt is buckled, neither the
light nor the chime comes on.
Front Passenger Seat Belt Reminder
Light
The vehicle may have a front passenger seat
belt reminder light near the passenger
airbag status indicator. See
Passenger
Sensing System 070.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
120 Instruments and Controls
will light either ON or OFF, or either the on
or off symbol, to let you know the status of
the front outboard passenger frontal airbag.
If the word ON or the on symbol is lit on
the passenger airbag status indicator, it
means that the front outboard passenger
frontal airbag is allowed to inflate.
If the word OFF or the off symbol is lit on
the passenger airbag status indicator, it
means that the passenger sensing system
has turned off the front outboard passenger
frontal airbag.
If, after several seconds, both status
indicator lights remain on, or if there are no
lights at all, there may be a problem with
the lights or the passenger sensing system.
See your dealer for service.
{Warning
If the airbag readiness light ever comes
on and stays on, it means that
something may be wrong with the airbag
system. To help avoid injury to yourself
or others, have the vehicle serviced right
away. SeeAirbag Readiness Light 0119
for more information, including important
safety information.
Charging System Light
The charging system light comes on briefly
when the ignition is turned on, but the
engine is not running, as a check to show
the light is working. It should go out when
the engine is started.
If the light stays on, or comes on while
driving, there may be a problem with the
electrical charging system. Have it checked
by your dealer. Driving while this light is on
could drain the battery.
When this light comes on, or is flashing, the
Driver Information Center (DIC) also displays
a message.
If a short distance must be driven with the
light on, be sure to turn off all accessories,
such as the radio and air conditioner. Find a
safe place to stop the vehicle.
Malfunction Indicator Lamp
(Check Engine Light)
This light is part of the vehicle’s emission
control on-board diagnostic system. If this
light is on while the engine is running, a
malfunction has been detected and the
vehicle may require service. The light should
come on to show that it is working when
the ignition is on and the engine is not
running. See Ignition Positions (Key Access)
0 221 or
Ignition Positions (Keyless Access) 0223.
Malfunctions are often indicated by the
system before any problem is noticeable.
Being aware of the light and seeking service
promptly when it comes on may prevent
damage.