Porsche P-80 2005, Manual

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911 Carrera (993) Model System
Climate Control Systems Diagnosis & Repair
Page 2.11
Compressor Clutch
When A/C is turned ON, there is a ten second delay before
energizing the compressor clutch and condenser fan.
When replacing the compressor clutch, be sure to
measure the air gap clearance between the thrust plate
and pulley. See the Repair Information for specifications.
Evaporator
Moisture condensing on the cold evaporator fins drains
out the bottom of the air distribution housing. Be sure that
this drain does not become obstructed or plugged. Water
coming from outlets at high blower fan speeds can
indicate drain blockage.
Evaporator fin temperatures cannot be allowed to drop
below the freezing point of water. If this happens, the
evaporator can become blocked with ice and airflow can
be reduced.
911 Carrere (993) On Board Diagnostics
The Heating-A/C Control Unit processor stores fault codes
when defects are detected. Self-diagnostics are not
permitted under the following conditions:
• Vehicle speed >0 mph
• Temperature in one or both mixing chambers >80° C
(176° F)
• Auxiliary blower temperature >95° C (203° F)
• Oil temperature >105° C (221° F)
The System Tester is required for troubleshooting. Fault
codes can be stored for the following parameters:
• Interior temperature sensor
• Left and right mixing chamber temperature sensors
• Evaporator temperature sensor
• Auxiliary blower temperature sensor
• Oil cooler temperature sensor
• Flap motor position sensors
• Left and right blower motors
• Condenser fan
• Oil cooler fan
• Auxiliary blower
A temperature sensor fault is stored only if the fault is
present continuously for at least 2.5 sec.
Blower motor voltage is monitored only when system
voltage is above 9.0V. A blower motor low voltage fault is
stored after 3 test cycles (3 seconds) have been carried
out when the blowers are turned ON.
The auxiliary blower is monitored. Monitoring continues
during the post-run phase (15 min.)
If one mixing chamber temperature sensor fails, the value
of the remaining sensor is used. If both sensors fail, the
mixing flaps are set to 40% open.
Both heater blowers are switched OFF when the tempera-
ture mixing flaps are not in the max. cool position.