1999 GMC SONOMA air conditioning

Table of Contents (cont'd)
Braking/Anti-lock Brakes (If Equipped)
Traction Control System
Steering
Driving Tips for Various Road ConditionsOff-Road Driving
Recreational Vehicle Towing
Loading Your Vehicle
Towing a Trailer Heating and Air Conditioning
Setting the Radio Clock
Radio/Cassette Player/CD PlayerRadio Theft-Deterrent Feature
Steering Wheel Controls (If Equipped)
Hazard Warning Flashers
Jump Starting
Towing Your VehicleEngine Overheating
Changing a Flat Tire
If You're Stuck
Problems on the Road
Section
3
Section
4
Section
5
Your Driving and the Road Comfort Controls and Audio Systems
iii

3-
3-1
Section 3 Comfort Controls and Audio Systems
In this section, you'll find out how to operate the comfort control and audio systems offered with your vehicle.
Be sure to read about the particular systems supplied with your vehicle.
3
-2 Comfort Controls
3
-2 Standard Climate Control System
3
-3 Optional Climate Control System
3
-4 Air Conditioning (If Equipped)
3
-4 Heating
3
-5 Defogging and Defrosting
3
-5 Ventilation System
3
-6 Audio Systems
3
-6 Setting the Clock for Systems
with SET Button
3
-6 Setting the Clock for Systems
with HR and MN Buttons
3
-7AM-FM Stereo3
-9AM-FM Stereo with Cassette Tape
Player (If Equipped)
3
-12 AM-FM Stereo with Cassette Tape Player and
Automatic Tone Control (If Equipped)
3
-16 AM-FM Stereo with Compact Disc Player and
Automatic Tone Control (If Equipped)
3
-20 Remote Cassette Tape Player (If Equipped)
3
-22 Theft-Deterrent Feature (If Equipped)
3
-24 Understanding Radio Reception
3
-24 Tips About Your Audio System
3
-25 Care of Your Cassette Tape Player
3
-26 Care of Your Compact Discs
3
-26 Care of Your Compact Disc Player
3
-26 Fixed Mast Antenna

3-3 Optional Climate Control System
Fan Control
The knob on the left side of the heating system
control panel controls the fan speed. To increase airflow,
turn the knob clockwise. To decrease airflow, turn
it counterclockwise.
Temperature Knob
The middle knob on the control panel lets you select
the relative temperature of the air flowing into the
passenger area of your vehicle. Turn the knob clockwise
toward the red area for warmer air. Turn the knob
counterclockwise toward the blue area for cooler air.Mode Knob
The right knob on the control panel allows you to
choose the direction of air delivery.
OFF: This setting turns the system off. Some outside
air will still enter the vehicle whenever the vehicle is
moving forward.
MAX A/C: This setting provides maximum cooling
with the least amount of work. MAX A/C recirculates
much of the air inside your vehicle so it cools quickly.
This setting directs most of the air through the
instrument panel vents and a small amount through
the floor vents.
A/C: This setting cools the air entering your vehicle and
directs most of the air through the instrument panel
vents and a small amount through the floor vents.
BI-LEVEL A/C: This setting cools the air
entering your vehicle and directs it through the heater
floor outlets as well as the instrument panel outlets.
VENT: This setting directs most of the air through
the instrument panel outlets and a small amount through
the floor outlets. The air conditioning compressor is not
working when VENT is selected.

3-4
HEATER: This setting directs most of the
warmed air through the heater floor outlets and some air
through the windshield defroster outlets.
BLEND: Airflow is divided equally between the
heater floor outlet and the windshield defroster outlets.
DEFROST: This setting directs most air through
the windshield defroster outlets and some through the
heater outlets.
Air Conditioning (If Equipped)
On hot days, open the windows long enough to let hot
inside air escape. This reduces the time it takes for your
vehicle to cool down. Then keep your windows closed
for the air conditioner to work its best.
For quick cool
-down on very hot days, use MAX A/C
with the temperature knob turned counterclockwise.
This setting should be used to keep odors and/or dust
from entering the vehicle. For normal cooling on
hot days, use A/C with the temperature knob
turned counterclockwise.On cool but sunny days, use BI
-LEVEL A/C to deliver
warm air to the floor and cooler air to the instrument
panel outlets.
If you have the VORTEC 4300 V6 engine, when the
air conditioner is on, you may sometimes notice slight
changes in your vehicle's engine speed and power. This
is normal because the system is designed to cycle the
compressor on and off to keep the desired temperature.
Heating
The heater works best if you keep your windows closed
while using it. On cold days, use HEATER with the
temperature knob turned clockwise. BLEND is useful in
cool weather when you have fog or ice on the
windshield or side windows.
If you use the optional engine coolant heater before
starting your engine, your heating system will produce
warmer air faster to heat the passenger compartment in
cold weather. See ªEngine Coolant Heaterº in the Index.

6-66
Name Usage
LT TRN Left Turn Signal Rear
RT TRN Right Turn Signal Rear
RR PRK Right Rear Parking Lamps
TRL PRK Not Used
LT HDLP Left Headlamp
RT HDLP Right Headlamp
FR PRK Front Parking Lamps
INT BAT I/P Fuse Block Feed
ENG I Engine Sensors/Solenoids, MAF,
CAM, PURGE, VENT
ECM B Engine Control Module, Fuel Pump
Module, Oil Pressure
ABS Anti
-Lock Brake System
ECM I Engine Control Module Injectors
BTSI Automatic Transmission Shift Lock
Control System
B/U LP Back
-Up Lamps
A/C Air Conditioning
W/W PMP Not Used
HORN Horn
IGN B Column Feed, IGN 2, 3, 4
RAP Retained Accessory Power
LD LEV Not UsedName Usage
OXYSEN Oxygen Sensor
IGN E Engine
MIR/LKS Mirrors, Door Locks
FOG LP Fog Lamps
IGN A Starting and Charging IGN 1
STUD #2 Accessory Feeds, Electric Brake
PARKLP Parking Lamps
LR PRK Left Rear Parking Lamps
IGN C Starter Solenoid, Fuel Pump,
PRNDL
HTDSEAT Not Used
HVAC HVAC System
TRCHMSL Not Used
RRDFOG Not Used
TBC Truck Body Computer
CRANK Clutch Switch, NSBU Switch
HAZLP Hazard Lamps
VECHMSL Vehicle Center High
-Mounted
Stoplamp
HTDMIR Heated Outside Mirrors
ATC Transfer Case (Four
-Wheel Drive)
STOPLP Stoplamps
RR W/W Not Used

7-47
Part C: Periodic
Maintenance Inspections
Listed in this part are inspections and services which
should be performed at least twice a year (for instance,
each spring and fall). You should let your dealer's
service department or other qualified service center do
these jobs. Make sure any necessary repairs are
completed at once.
Proper procedures to perform these services may be
found in a service manual. See ªService and Owner
Publicationsº in the Index.
Steering, Suspension and Front Drive Axle
Boot and Seal Inspection
Inspect the front and rear suspension and steering
system for damaged, loose or missing parts, signs of
wear or lack of lubrication. Inspect the power steering
lines and hoses for proper hook
-up, binding, leaks,
cracks, chafing, etc. Clean and then inspect the drive
axle boot seals for damage, tears or leakage. Replace
seals if necessary.
Exhaust System Inspection
Inspect the complete exhaust system. Inspect the body
near the exhaust system. Look for broken, damaged,
missing or out
-of-position parts as well as open seams,
holes, loose connections or other conditions which could
cause a heat build
-up in the floor pan or could let
exhaust fumes into the vehicle. See ªEngine Exhaustº in
the Index.
Engine Cooling System Inspection
Inspect the hoses and have them replaced if they are
cracked, swollen or deteriorated. Inspect all pipes, fittings
and clamps; replace as needed. Clean the outside of the
radiator and air conditioning condenser. To help ensure
proper operation, a pressure test of the cooling system and
pressure cap is recommended at least once a year.