Troubleshooting - Porsche 911 TURBO - 1975 WORSHOP Manual

Heater
TROUBLESHOOTING AUTOMATIC HEATER CONTROLS
Checking Interior Sensor Checking Heat Sensor in Heater
Flap Housing
1 -Remove interior sensor.
1 -Remove control unit.
2 -Connect ohmmeter to 2-pole plug of
heat sensor. The resistance must be
135 ohm with warm engine at 1000C.
Replace heat sensor if resistance is way
off (see "Checking Interior Sensor").
2 -Using an ohmmeter with an appropriate
testing range, check the resistance bet-
ween both coaxial connections on the
sensor (use test points). The resistance
is very dependent on the temperature and
should be about 1.5 kOhm at room
temperature. Replace the temperature
sensor if the resistance is about CD ohm
(interuption in sensor) or about 0 ohm
(short circuit in sensor).
Note
An interruption in one of the sensors or in the
wires to the control unit will fake a too low
or, a short circuit, a too high inside tempera-
ture. This will result in an improper movement
of the heater lever up or down.
80-5 Checking Automatic Heater Controls
Printed in Germany