2021 CHEVROLET SILVERADO 2500HD heater

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
310 Vehicle Care
Caution
If the air cleaner/filter is off, dirt can
easily get into the engine, which could
damage it. Always have the air cleaner/
filter in place when driving.
Cooling System
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement.
The cooling system allows the engine to
maintain the correct working temperature.
{Warning
An underhood electric fan can start up
even when the engine is not running and
can cause injury. Keep hands, clothing,
and tools away from any underhood
electric fan.
1. Engine Cooling Fan (Out of View)
2. Coolant Surge Tank and Pressure Cap
{Warning
Do not touch heater, radiator, a/c pipes
or hoses, or other engine parts. They can
be very hot and can burn you. Do not
run the engine if there is a leak; all
coolant could leak out. That could cause
an engine fire and can burn you. Fix any
leak before driving the vehicle.
Engine Coolant
The cooling system in the vehicle is filled
with DEX-COOL engine coolant. This coolant
is designed to remain in the vehicle for
5 years or 240 000 km (150,000 mi),
whichever occurs first.
The following explains the cooling system
and how to check and add coolant when it
is low. If there is a problem with engine
overheating, seeEngine Overheating 0312.
What to Use
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain water or
the wrong mixture, the engine could get
too hot but there would not be an
overheat warning. The engine could catch
fire and you or others could be burned.
Use a 50/50 mixture of clean, drinkable
water and DEX-COOL coolant. This mixture:
.Gives freezing protection down to −37 °C
(−34 °F), outside temperature.
.Gives boiling protection up to 129 °C
(265 °F), engine temperature.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Vehicle Care 313
If the decision is made not to lift the hood
when this warning appears, get service help
right away. SeeRoadside Assistance Program
0 404.
If the decision is made to lift the hood,
make sure the vehicle is parked on a level
surface.
Check to see if the engine cooling fans are
running. If the engine is overheating, the
fans should be running. If they are not, do
not continue to run the engine and have the
vehicle serviced.
If the engine or transmission detects an
impending hot fluid condition, then the
transmission may force upshifts to limit
temperatures. Downshifts may also be
prevented in this instance. Normal operation
may continue unless the display indicates
there is a hot condition and engine should
be idled.If Steam is Coming from the Engine
Compartment
{Warning
Steam and scalding liquids from a hot
cooling system are under pressure.
Turning the pressure cap, even a little,
can cause them to come out at high
speed and you could be burned. Never
turn the cap when the cooling system,
including the pressure cap, is hot. Wait
for the cooling system and pressure cap
to cool.
If No Steam is Coming from the Engine
Compartment
The ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE
message, along with a low coolant
condition, can indicate a serious problem.
If there is an engine overheat warning, but
no steam is seen or heard, the problem may
not be too serious. Sometimes the engine
can get a little too hot when the vehicle:
.Climbs a long hill on a hot day.
.Stops after high-speed driving.
.Idles for long periods in traffic.
.Tows a trailer; see Trailer Towing0272.
If the ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE
message appears with no sign of steam, try
this for a minute or so: 1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the highest fan
speed. Open the windows as necessary.
3. When it is safe to do so, pull off the road, shift to P (Park) or N (Neutral) and
let the engine idle.
If the temperature overheat gauge is no
longer in the overheat zone or an overheat
warning no longer displays, the vehicle can
be driven. Continue to drive the vehicle
slowly for about 10 minutes. Keep a safe
vehicle distance from the vehicle in front.
If the warning does not come back on,
continue to drive normally and have the
cooling system checked for proper fill and
function.
If the warning continues, pull over, stop, and
park the vehicle right away.
If there is still no sign of steam and the
vehicle is equipped with an engine driven
cooling fan, push down the accelerator until
the engine speed is about twice as fast as

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Index 423
Driver Mode Control Light . . . . . . . . . . . . . . . . 117
DrivingAssistance Systems . . . . . . . . . . . . . . . . . . . . 257
Better Fuel Economy . . . . . . . . . . . . . . . . . . . 207
Characteristics and Towing Tips . . . . . . . . 268
Defensive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Hill and Mountain Roads . . . . . . . . . . . . . . 215
If the Vehicle is Stuck . . . . . . . . . . . . . . . . . 216
Impaired . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Loss of Control . . . . . . . . . . . . . . . . . . . . . . . . 210
Off-Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Off-Road Recovery . . . . . . . . . . . . . . . . . . . . . 210
Vehicle Load Limits . . . . . . . . . . . . . . . . . . . . . 217
Wet Roads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Winter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Dual Automatic Climate Control
System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
E
E85 or FlexFuel . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Electric Parking Brake . . . . . . . . . . . . . . . . . . . . 240
Electric Parking Brake Light . . . . . . . . . . . . . . . 113
Electrical Equipment, Add-On . . . . . . . . . . . . 297
Electrical SystemEngine Compartment Fuse Block . . . . . . . 329
Fuses and Circuit Breakers . . . . . . . . . . . . . 329
Instrument Panel Fuse Block . . . . . . 332, 334
Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328 Electronic Stability Control (ESC) Off
Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Emergency OnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413
Engine Air Cleaner/Filter . . . . . . . . . . . . . . . . . . . . . . 309
Check Light (Malfunction Indicator) . . . . . 111
Compartment Overview . . . . . . . . . . . . . . . . 304
Coolant Temperature Gauge . . . . . . . . . . . 108
Coolant Temperature Warning Light . . . . 116
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . 310
Drive Belt Routing . . . . . . . . . . . . . . . . . . . . 400
Exhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Oil Life System . . . . . . . . . . . . . . . . . . . . . . . . 307
Oil Pressure Gauge . . . . . . . . . . . . . . . . . . . . 107
Oil Pressure Light . . . . . . . . . . . . . . . . . . . . . . . 117
Overheated ProtectionOperating Mode . . . . . . . . . . . . . . . . . . . . . 314
Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
Power Messages . . . . . . . . . . . . . . . . . . . . . . . 126
Running While Parked . . . . . . . . . . . . . . . . . 232
Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Engine Air Filter Life System . . . . . . . . . . . . . 308
Entry Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Equipment, Towing . . . . . . . . . . . . . . . . . . . . . . 276
Event Data Recorders . . . . . . . . . . . . . . . . . . . . . 411 Exit Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Extended Parking . . . . . . . . . . . . . . . . . . . . . . . . . 231
Extender, Seat Belt . . . . . . . . . . . . . . . . . . . . . . . 56
Exterior Cargo Lamps . . . . . . . . . . . . . . . . . . . . 139
Exterior Lamp Controls . . . . . . . . . . . . . . . . . . . .134
Exterior Lamps Off Reminder . . . . . . . . . . . . 136
Exterior Lighting Battery Saver . . . . . . . . . . .142
F
Fan
Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Filter,
Engine Air Cleaner . . . . . . . . . . . . . . . . . . . . . 309
Fixed Mast Antenna . . . . . . . . . . . . . . . . . . . . . . 153
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Flashers, Hazard Warning . . . . . . . . . . . . . . . . . 137
Flat Tire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355 Changing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
FlexFuel E85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Floor Console Storage . . . . . . . . . . . . . . . . . . . . . 93
Floor Mats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .381
Fluid
Automatic Transmission . . . . . . . . . . . . . . . 308
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Four-Wheel Drive Transfer Case . . . . . . . . 236
Power Steering . . . . . . . . . . . . . . . . . . . . . . . . 314
Washer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
424 Index
Fog Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138
Folding Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Forward Collision Alert (FCA) System . . . . 257
Four-Wheel Drive . . . . . . . . . . . . . . . . . . . 236, 320
Four-Wheel-Drive Light . . . . . . . . . . . . . . . . . . . . 114
Frequency StatementRadio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409
Front Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
Front Fog Lamp Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Front Seats
Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Heated and Ventilated . . . . . . . . . . . . . . . . . . 49
Fuel Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Economy, Driving for Better . . . . . . . . . . . 207
Filling a Portable Fuel Container . . . . . . . 267
Filling the Tank . . . . . . . . . . . . . . . . . . . 265, 266
Foreign Countries . . . . . . . . . . . . . . . . . . . . . . 264
Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Low Fuel Warning Light . . . . . . . . . . . . . . . . 118
Prohibited Fuels . . . . . . . . . . . . . . . . . . . . . . . 264
Recommended . . . . . . . . . . . . . . . . . . . . . . . . . 263
Top Tier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Full-Size Spare Tire . . . . . . . . . . . . . . . . . . . . . . . 366
Fuses
Engine Compartment Fuse Block . . . . . . . 329
Fuses and Circuit Breakers . . . . . . . . . . . . . 329 Fuses (cont'd)
Instrument Panel Fuse Block . . . . . . 332, 334
G
Garage Door Opener . . . . . . . . . . . . . . . . . . . . . . 131
Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Gas Strut(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Gauges Engine Coolant Temperature . . . . . . . . . . . 108
Engine Oil Pressure . . . . . . . . . . . . . . . . . . . . 107
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Odometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Speedometer . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Tachometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Trip Odometer . . . . . . . . . . . . . . . . . . . . . . . . . 106
Voltmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Warning Lights and Indicators . . . . . . . . . 102
General Information Service and Maintenance . . . . . . . . . . . . . . 383
Towing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
Vehicle Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Glass Replacement . . . . . . . . . . . . . . . . . . . . . . . 323
Global Positioning System (GPS) . . . . . . . . . 168
Glove Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
GM Mobility Reimbursement Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404
Guidance Problems with the Route . . . . . . . . . . . . . . 169
H
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Hazard Warning Flashers . . . . . . . . . . . . . . . . . 137
HD Radio Technology . . . . . . . . . . . . . . . . . . . . . 151
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Head-up Display . . . . . . . . . . . . . . . . . . . . . . . . . . 123
HeadlampsAiming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . . 324
Daytime Running Lamps (DRL) . . . . . . . . . 136
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Headlamps, Front Turn Signal,Sidemarker, and Parking Lamps . . . . . . 325
High-Beam On Light . . . . . . . . . . . . . . . . . . . . 118
High/Low Beam Changer . . . . . . . . . . . . . . 136
Lamps On Reminder . . . . . . . . . . . . . . . . . . . . 118
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Steering Wheel . . . . . . . . . . . . . . . . . . . . . . . . . 96
Heated and Ventilated Front Seats . . . . . . . 49
Heated Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Heater Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199, 201
High-Beam On Light . . . . . . . . . . . . . . . . . . . . . . 118
Hill and Mountain Roads . . . . . . . . . . . . . . . . . 215
Hill Descent Control (HDC) . . . . . . . . . . . . . . . 244