GMC chevrolet camaro 2000 Service Manual page 186

HVAC
Heating, Ventilation and Air Conditioning 1-89
Description and Operation
J
A/C System Description
The heating, ventilation and air conditioning (HVAC)
system delivers air that has been heated or cooled and
dehumidified for occupant comfort. The HV AC
system also provides the following features:
• Ventilation
• Windshield defrosting
• Side window defogging
During most operating condition, the blower motor
draws the outside air through the heater and air
conditioning module. The forward movement of the
vehicle forces additional air into the vehicle. The
following actions occur in the evaporator core when
the compressor is on:
• The air is filtered
• The air is dehumidified
• The air is cooled to about 2°C (35°F)
Some of the air then passes through the heater core
where the flow of hot coolant reheats the air.
Depending on the temperature door position, the
heated air is mixed with cold air from the evaporator
before the air enters into the passenger compartment.
The air enters the passenger compartment through
\ the upper, lower, or defroster outlets. This provides
) positive air flow even if the windows are closed.
)
When the Recirc mode is selected, most of the air
entering the evaporator and heater core module
is recirculated from the passenger compartment.
Recirculated air is most likely cooler and dryer than
outside air in very hot weather.
Heater Core Description
The heater core is the main component of the heater
system. The heater core is located inside of the
heater and evaporator module. Engine coolant is
pumped into the heater core from the engine whenever
the engine is operating. The heater core fins transfers
the heat from the engine coolant to the air passing
over the heater core. The heater core has specific inlet
and outlet tubes. The placement of the heater hoses
should be noted prior to servicing the heater core
or the heater hoses.
The temperature control is linked to the temperature
valve by a flexible control cable. When you rotate
temperature control counterclockwise to the full COLD
position, the temperature valve is held snugly
against the air entrance to the heater core. The
following actions occur:
• All of the airflow from the evaporator bypasses the
heater core.
• No heat transfer occurs.
When you turn the temperature control away from the
full COLD position, the temperature valve begins to
direct air to the heater core. This action allows
air to flow through the heater core. The farther the
temperature control is rotated clockwise, the more the
temperature valve directs air through the heater
core. The air discharge is warmer when most of the
airflow is heated in this manner. The air discharge
is warmer because the heated and unheated air flows
join and mix together thoroughly beyond the
heater core.
When you rotate the temperature lever clockwise to
the full HOT position, the temperature valve blocks off
the passage that allows air to bypass the heater
core. This action causes passage of the airflow
through the heater core.