Porsche 1972 911 Workshop Manual page 921

T R O U B L E S H O O T I N G A U T O M A T I C H E A T I N G C O N T R O L S
C h e c k i n g I n t e r i o r S e n s o r
1. Remove interior sensor.
2. Using a n o h m m e t e r with an appropriate
testing range, check t h e resistance bet-
ween both coaxial connections on t h e
sensor (use test points). T h e resistance
is very dependent on t h e temperature and
should b e about 1.5 kOhm a t room
sensor if the resistance is about w ohm
(open circuit in sensor) or about 0 ohm
(short circuit in sensor).
t h e
temperature
E l e c t r i c a l E q u i p m e n t
C h e c k i n g H e a t S e n s o r i n H e a t e r
F l a p H o u s i n g
1. Remove control unit.
Connect o h m m e t e r t o 2- pole plug of
2 .
h e a t sensor. T h e resistance must b e
135 ohm with warm engine a t
o
212 F. Replace h e a t sensor if resistance
is way off (see "Checking Interior
Sensor").
N o t e
An open circuit i n o n e of t h e sensors or in t h e
wires t o t h e control unit will show a too low
inside temperature or, a short circuit, a too
high inside temperature. This will result i n
a n improper movement of t h e heater lever
u p or down.
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