Porsche P-80 2005, Manual

Page: 51 / 108

Sports Cars System
Climate Control Systems Diagnosis & Repair
Page 3.17
Footwell Outlet Temperature Sensor
The footwell outlet temperature sensor sends a signal to
the A/C Control Unit for footwell outlet air temperature.
The sensor is located on the lower left side of the air
distribution housing.
Solar Sensor
Solar intensity is detected by photo diodes in the solar
sensor. The signal from the solar sensor is used along
with temperature measurements to improve the A/C
system’s ability to accurately judge the expected heat
load. An increase in sensed solar radiation causes the A/C
Control Unit to command an increase in blower speed.
Changes in solar intensity register after a delay of typically
3-8 seconds. This prevents unnecessary adjustments by
the automatic A/C system in response to transient condi-
tions. The solar sensor is located on the top of the dash in
the center.
Air Control Flap Position Sensors
Automatic Climate Control system air control flap motors
have feedback position sensors built-in. The position
sensor is a potentiometer which provides an analog signal
to the A/C Control Unit for flap position.
There are four air control flap position sensors in 911
Carrera (996)/(997) and Boxster (986)/(987) air distribu-
tion housings:
• Fresh air/recirculation flap position sensor
• Footwell/defrost flap position sensor
• Temperature flap position sensor
• Central flap position sensor
Actuators
Compressor Clutch
An electromagnetic clutch engages and drives the
compressor. The clutch hub and spring plate are attached
to the compressor shaft and turn with it. The clutch pulley
is driven by the serpentine accessory belt. When the elec-
tromagnetic clutch coil is energized, the spring plate and
hub are attracted to the pulley by a strong magnetic field
and they both rotate together.
The DME controls compressor clutch engagement. The
A/C Control Unit also receives a signal and knows the
clutch status. The clutch can be removed and replaced
separately.