GMC chevrolet camaro 2000 Service Manual page 244

HVAC
• Power is routed from the HVAC fuse in the fuse
block to the mode control switch.
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The mode control switch breaks the circuit when
the switch is in the OFF position. The switch
closes the circuit in all other positions.
• From the mode control switch the circuit goes to
the blower motor speed control switch.
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When the blower motor speed control switch is
turned to the LOW setting, voltage is conducted
to the resistor. At the resistor, the voltage passes
through all three resistors and is reduced to
provide the low blower motor speed.
• When the blower switch is in either of the
two medium speed positions, the switch closes.
This action sends voltage through one or
two of the resistors. Because the current follows
the path of least resistance, the circuit branch that
leads directly to all three resistors becomes
ineffective. At this point the current bypasses
either one or two resistors, depending upon which
medium speed position is selected. The reduced
resistance increases the current flow and
blower motor speed.
• When the blower motor switch is turned to the
HIGH setting, the action energizes the high bl.ower
relay. Power is taken from a separate circuit
that is protected by a fusible link. The separate
power circuit is hot at all times. The circuit has the
capacity to handle the current demands of the
blower motor at high speed.
• The circuit to the blower motor is completed to
ground at the instrument panel through the
instrument panel wiring harness.
Control Assembly Description (Chevrolet)
A/c,
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283258
The heating, ventilation and air conditioning (HVAC)
control head uses three knobs and one push button in
order to control the following features:
• The air delivery
• The air temperature
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The blower motor speed
• The rear defroster
HVAC Systems - Manual 1-147
Temperature Control Knob
The temperature control knob regulates the HVAC
system air temperature. The knob is located in
the center of the HVAC control head. A temperature
control cable mechanically links the knob to the
temperature valve (door).
" Turn the knob toward the driver for heat.
" Turn the knob toward the passenger for air
conditioning (A/C).
Mode Control Knob
The mode control knob is located on the right side of
the HVAC control head. The following are the
eight different modes:
"OFF
"MAX
.. A/C
., Bl-LEVEL A/C
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VENT
., HEATER
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DEFROST/BLEND
., DEFROST
OFF
The following actions occur when the knob is in the
OFF position:
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The blower motor does not operate.
.. Electrical power is not supplied to the
blower motor.
.. An A/C request signal is not sent to the powertrain
control module (PCM).
• A small amount of air is forced into the HVAC
module by the forward movement of the vehicle.
The air is discharged through the heater and
defrost outlets.
MAX
The following actions occur when the knob is in the
MAX position:
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An A/C request signal is sent to the PCM.
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The blower motor operates in one of four blower
motor speed control settings.
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Air is discharged only from the instrument panel
air outlets.
" In order to provide MAX A/C, most of the air
entering the HV AC module is taken from the
vehicle interior (re-circulated). This interior air is
cooler than the outside air. MAX is the only setting
at which the air is re-circulated.
Use the MAX setting when the following
conditions exist:
., High temperature
.. High humidity
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The outside air has an objectionable odor
A/C
The A/C setting functions the same as the MAX
setting, except that only outside air enters the HVAC
module. There may be a slight reduction of blower
noise compared to the MAX setting because the
re-circulation valve (door) is closed.