2003 GMC SONOMA air conditioning

Heating
Turn the center knob clockwise or counterclockwise to
raise or lower the temperature on the inside of your
vehicle.
When it’s cold outside 0°F(−18°C) or lower, use the
engine coolant heater, if equipped, to provide warmer air
faster to your vehicle. An engine coolant heater warms
the coolant that the engine uses to provide heat to
warm the inside of your vehicle. For more information,
seeEngine Coolant Heater on page 2-24.
Cooling
On hot days, open the windows to let hot inside air
escape; then close them. This helps to reduce the time
it takes for your vehicle to cool down. It also helps
the system to operate more efficiently.
A/C (Air Conditioning):Turn the knob to the A/C
position to turn the air-conditioning system on or
off. When the system is on, this setting cools and
dehumidies the air entering your vehicle and directs
it through theoor outlets as well as the instrument
panel outlets.
MAX A/C (Maximum Air Conditioning):This mode
recirculates much of the air inside your vehicle so
it cools quickly. It directs most of the air through the
instrument panel outlets and a small amount through
theoor outlets.
-(Blend):Use this mode to direct half the air to the
windshield and half to theoor outlets. Close the
center outlets to help defrost the side windows more
quickly. In this mode, the system will automatically force
outside air into your vehicle and it will also run the
air-conditioning compressor, unless it falls below the
temperature at which air conditioning is effective.
You may notice a slight change in engine performance
when the air-conditioning compressor shuts off and
turns on again. This is normal. The system is designed
to make adjustments to help with fuel economy while
still maintaining the selected temperature.
For quick cool down on hot days, do the following:
1. Select A/C.
2. Select the coolest temperature.
3. Select the highest fan speed.
On cool, but sunny days, the sun may warm the upper
part of your body, but the lower part may not be
warm enough. To remedy this, do the following:
1. Select the bi-level mode.
2. Select the temperature.
3. Select the fan speed.
The air-conditioning system removes moisture from the
air, so you may sometimes notice a small amount of
water dripping underneath your vehicle while idling
or after turning off the engine. This is normal.
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2003 - Sonoma OM

Defogging and Defrosting
To circulate outside air and to help clear the windshield
quickly, do the following:
1(Defrost):This mode directs most of the air to the
windshield and the side window outlets, with only a
little air directed to theoor outlets.
-(Blend):This mode can be used on cool, humid
days to keep the windshield and side windows clear.
1. Select the blend mode.
2. Select the temperature.
3. Select the highest fan speed.
Outlet Adjustment
Theow through outlets on your vehicle allow outside
air to enter your vehicle while it is moving. Outside
air will also enter your vehicle while the air-conditioning
compressor is running.
Use the thumbwheels located in the center and on the
sides, to change the direction of the airowing through
the outlets.
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2003 - Sonoma OM

Fuse Usage
TRL TRN Trailer Left Turn
TRR TRN Trailer Right Turn
TRL B/U Trailer Back Up Lamps
VEH B/U Vehicle Back Up Lamps
HDLP PWR Headlamp PowerFuse Usage
RT TURN Right Turn Signal Front
LT TURN Left Turn Signal Front
HDLP W/W Not Used
LT TRN Left Turn Signal Rear
RT TRN Right Turn Signal Rear
RR PRK Right Rear Parking Lamps
TRL PRK Trailer Park Lamps
LTHDLP Left Headlamp
RTHDLP Right Headlamp
FRPRK Front Parking Lamps
INT BAT Instrument Panel 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
F/PUMP Fuel Pump
DRL Daytime Running Lamps
A/C Air Conditioning
HORN Horn
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2003 - Sonoma OM

ApplicationCapacities
English Metric
Automatic Transmission
Drain and Refill5.0 quarts 4.7 L
Differential Fluid
Rear Axle
Front Axle4.0 pints
2.6 pints1.9 L
1.2 L
Air Conditioning Capacity
Air Conditioning Refrigerant R134a1.8 lbs 0.79 kg
All capacities are approximate. After refill, the levelmustbe checked.
All capacities are approximate. When adding, be sure tofill to the appropriate level or as recommended in
this manual. SeePart E: Maintenance Record on page 6-35
Capacities and Specications
Type VIN Code Transmission Spark Plug Gap Firing Order
2200
L4HAutomatic
Manual0.040 inches
(1.01 mm)1-3-4-2
4300
V6XAutomatic
Manual0.060 inches
(1.52 mm)1-6-5-4-3-2
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2003 - Sonoma OM

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 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. SeeService Publications
Ordering Information on page 7-9.
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, chang, 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 theoor pan or could let
exhaust fumes into the vehicle. SeeEngine Exhaust
on page 2-37.
Fuel System Inspection
Inspect the complete fuel system for damage or leaks.
Engine Cooling System Inspection
Inspect the hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect all pipes,
ttings 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.
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