2000 CHEVROLET ASTRO compressor

3-3
BI-LEVEL: This setting brings in outside air and
blows it out through the heater floor vents and the
instrument panel vents. If you move the temperature
knob between hot and cold, cooler air will come out of
the upper vents while warmer air comes out of the floor
vent. The air conditioning compressor may operate in
this setting to cool the air.
VENT: The air comes out at the vents on your
instrument panel. The air conditioning compressor will
not run in this position. Adjust the temperature knob for
warmer or cooler air.
HEATER: Most of the air comes out near the
floor. The rest comes out from the defroster vents under
the windshield and at the front side windows.
BLEND: With this setting, the heated outside air
comes out of both the heater vents and defroster vents.
Adjust the temperature knob for warmer or cooler air.
The air conditioning compressor may operate in this
setting to dehumidify the air.
DEFROST: This setting operates the defroster.
Most of the air comes out near the windshield, with
some going to the floor vents and front side windows.
The air conditioning compressor may operate in this
setting to dehumidify the air.
Heating System
If your vehicle does not have air conditioning, your
heater controls will look like this.
Fan Knob
This control has four positions. To increase airflow,
turn the knob toward HI. To decrease airflow, move it
toward LO.
Temperature Knob
This knob is next to the fan knob. It controls the
temperature of the air flowing into your vehicle. Turn
the knob clockwise for warmer air. Turn the knob
counterclockwise for cooler air.

3-5 Rear Air Conditioning System (Option)
You may have rear air conditioning. The rear air
conditioning switch is located to the right of the heater
controls. Turn the switch toward HIGH for higher
airflow in the rear area. Turn the switch to the OFF
position to turn the system off.
Air Conditioning
Before using your vehicle's air conditioning, open the
windows to clear the vehicle of hot air. This reduces the
time it takes for your vehicle to cool down. Then keep
your windows closed for the air conditioner to work at
its best.
You can use MAX A/C with the temperature knob in the
blue area when it's really hot outside and you need to
cool the inside air quickly. MAX A/C lets in only a little
air from the outside.
If you first use MAX A/C, you can then use A/C with
the temperature knob in the blue are as soon as the
vehicle has cooled down, so outside air will be going
through your vehicle.
If your vehicle has rear air conditioning, setting it on
LOW may enhance the front A/C performance by
allowing trapped refrigerant in the rear lines to circulate.
The rear air conditioning system will only send cooled
air if the front system is on. It can still be used to
circulate air, even if the front system is off.
When the air conditioning, DEFROST or BLEND is on,
you may notice a slight increase or decrease in engine
speed, due to compressor operation. This is normal
because the system is designed to cycle the compressor
on and off to keep the desired temperature.

3-6 Heating
On cold days, use HEATER with the temperature knob
in the red area. Outside air will be brought in through
the floor outlets. The heater works best if you keep your
windows closed while using it.
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.
Defrosting
Use DEFROST to remove fog or ice from the
windshield quickly in extremely cold conditions. The
temperature knob should be in the red area and the fan
control toward high. The air conditioning compressor
may operate in this setting to dehumidify the air.
The BLEND setting is useful for cold weather with a
large number of passengers or very humid conditions to
help keep the windshield clear.
Ventilation System
For mild outside temperatures when little heating or
cooling is needed, use VENT to direct outside air
through your vehicle. Air will flow through the
instrument panel vents.
Your vehicle's flow
-through ventilation system supplies
outside air to the inside of your vehicle when it is
moving. With the side windows closed, air will flow into
the front air inlet grilles at the base of the windshield,
through the vehicle and out the rear air exhaust valve.
Outside air will also enter the vehicle when the heater or
the air conditioning fan is running.

6-66
Fuse/Circuit
Breaker Usage
ECM
-B Fuel Pump Relay and Motor,
VCM, Oil Pressure
Switch/Sender
HORN Horn Relay and Horn
A/C COMP A/C Enable Relay
and Compressor
RR HTR/AC Rear Heater and A/C
ATC Active Transfer Case
FRT HVAC Front Heater and A/C
ENG
-I Oxygen Sensors, Camshaft
Position Sensor, Mass Air Flow
Sensor, Evaporative Emission
Canister Vent Solenoid
IGN
-E A/C Enable Relay Coil
ECM
-I Fuel Injectors 1-6, Crankshaft
Position Sensor, VCM, Coil
Driver Module (EST),
Ignition CoilFuse/Circuit
Breaker Usage
RH HDLMP Right Headlamp
LH Headlamp Left Headlamp
DIODE
-A/C Coil A/C
LIGHTING Courtesy Fuse, Pwr. Adj.
Mirrors Fuse, TBC
-Battery Fuse
BATT Power ACCY CB, Stop/Hazard
Fuse, Auxiliary Power Fuse,
Cigarette Lighter Fuse,
Radio Battery Fuse
IGN A Starter Relay, Ignition Switch
IGN B Ignition Switch
ABS Electronic Brake
Control Module
RAP Radio Accy, Power Windows
HTD MIR/RR
DEFOGRear Window Defogger,
HVAC Control Head
*A fuse puller is included in the underhood electrical
center. You will also find spare fuses.