Sensors; Aspiration; B Series Description - Pontiac FIREBIRD 1972 Service Manual

AUTOMATIC TEMPERATURE CONTROL 1B-25
ASPIRATION
The in-car sensor assembly is connected by a hose to the
aspirator (Fig. 1B-23) located on the top of the heater
case. The aspirator is designed to pass a small amount of
air flow from the cold air portion of the heater case toward
the front of the car. This flow of air causes a slight vacuum
effect at the end of the aspirator to which the in-car sensor
hose is connected. The result is that air from the passenger
compartment is pulled through the sensor grille, across
the sensor, through the hose and aspirator toward the
front of the car. In this manner, the in-car sensor will be
sensing true in-car air and adjusting the signal to the
programmer amplifier to compensate for in-car tempera-
ture changes.
---
TO COWL
AREA
FROM
HEATER
CASE
FROM
IN-CAR
SENSOR
J
FROM
HEATER
CASE
Fig. 1 6 - 2 3 Aspirator
B SERIES DESCRIPTION
Due to the differences in programmer and control panel
design and the means by which the signal at the input to
the programmer amplifier regulates the ATC systems on
the B and G Series, the two systems are described sepa-
rately.
The following information describes the B Series ATC
system components and operation. Operation and compo-
nents of the G Series ATC system are described under G
SERIES DESCRIPTION.
BASIC SYSTEM OPERATION
The numbers on the temperature dial thumbwheel control
located on the control head (control panel, Fig. 1B-24)
indicate the various temperatures which can be obtained
TEMPERATURE D I A L
/
lTHUMBWHEEL'
Fig. 1 8 - 2 4 ATC Control Panel
-
8 Series