Porsche P-80 2005, Руководство пользователя

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911 Carrera (993) Model System
Climate Control Systems Diagnosis & Repair
Page 2.5
Air Control Flaps
Each duct has a temperature mixing flap to regulate the
hot air supply. The temperature mixing flaps are moved by
a servo motor controlled by the processor. To avoid
drawing in exhaust fumes when driving in reverse, the
temperature mixing flaps are moved to the “max cold”
position when reverse gear is selected.
When the ignition is turned OFF, the drive motor sets the
temperature mixing flaps to the full-cold position and
closes the hot air ducts. Each hot air duct has an integral
mechanical flap which is actuated automatically by air flow
rate and the heating or cooling air requirement. There is
no electrical control for these flaps.
The fresh air/recirculation flap is located in the fresh air
inlet of the air distribution housing and is controlled by
vehicle speed and the blower speed setting. The fresh
air/recirculation flap is fully closed during maximum
cooling, maximum heat and air recirculation operation.
The left and right footwell outlets have motor-controlled
flaps to infinitely vary the outlet air volume. Also, a defrost
flap is located centrally in the air distribution housing near
the panel center outlet. The flap is motor-driven and
infinitely variable, and directs air to the defrost or face
vent. Left and right side outlets are opened and closed by
adjusting the outlet grille openings. All flaps except the
bypass air flap are controlled by electric servo motors.
Fresh Air Mode
Air can be drawn into the air distribution housing from two
inlets - outside (fresh) air, and inside (recirculation) air.
When the fresh air mode is selected, outside air is drawn
into the vehicle from the intake air duct, located in the
plenum in front of the windshield. All air passes through
the particle filter.
Air Recirculation Mode
Depressing the recirculation switch on the Heater-A/C
Regulator selects the recirculation mode. The recirculation
mode prevents outside air intake and increases the
cooling efficiency of the A/C. It also prevents unpleasant
odors from entering the vehicle interior.
Defrost Mode
Depressing the defrost button on the Heater-A/C Regulator
selects the defrost mode. This mode directs most outlet
air to the windshield. Air conditioning is engaged to reduce
humidity and to speed demisting.The processor in the
Heating-A/C Unit controls the speed of these blowers to
ensure a relatively constant rate of airflow into the
passenger compartment independent of engine speed.
The two blowers in the air distribution housing run continu-
ously at low speed.
Heating-A/C Control Unit Operation
Automatic Climate Control Panel
911 Carrera (993) models feature air conditioning
systems with automatic temperature control. A Heating-
A/C Control Unit contains an electronic processor which
receives inputs from sensors and provides outputs to
control actuators. Sensor input information includes
interior and outlet air temperature. The interior air temper-
ature value is compared with the passenger-selected
value. If the two values are different, the Heating-A/C Unit
commands electric servo motors to move air distribution
flaps to increase or decrease the outlet air temperature.
The Heating-A/C Control Unit is located in the instrument
panel and has the manual passenger’s controls.
Passengers can select the desired temperature, blower
speed and air distribution conditions. The system will
maintain the set temperature as conditions change. A/C
systems monitor and control some or all of the following in
order to function properly: compressor clutch
engagement, refrigerant temperature, refrigerant
pressure, and air temperature at various locations.
Depending upon the system, other sensors such as a
solar sensor and air control flap position sensors may also
be used.
When A/C is turned ON, there is a ten second delay before
energizing the compressor clutch and condenser fan.