Air Conditioning Function Switch - Aston Martin DB7 Workshop Manual

Air Conditioning
In Car Controls
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Air Conditioning Function Switch
The air conditioning function switch (Fig. 4) has
five positions: Economy (ECO), Air conditioning
(AC), Manual (MAN), Re-circulation and Demist
(DEM). These settings have thefol lowing functions:
ECO (Economy) Inthissettingtheairconditioning
compressor is switched off. No cooling is
available but incoming air may be heated to
the selected temperature. This mode puts a
minimum load on the engine. Pin 23 at the
ECM is earthed through the switch to select
economy mode.
AC This setting allows the heating and cooling
functions to be performed automatically,
the required in-cartemperature is maintained
and the air is dehumidified. Pin 26 at the
ECM is earthed through the switch to select
this mode.
M A N (Manual) In the Manual mode the fan speed
and temperature control can be set at any
level and heating or cooling w i l l be
performed despite the internal temperature
of the car. Pins 26 and 19 at the ECM are
earthed through the switch to select this
mode
V (Re-circulation) With this setting selected
the external air inlets are closed and
conditions are maintained by circulating
the air within the car. Heating and cooling
functions are controlled automatically to
give the required in-cartemperature. Pins 9
and 26 at the ECM are earthed through the
switch to select the manual Re-circulation.
DEM (Demist) Air is directed directly onto the
screen in this m o d e . Air speed and
temperature depend on the selected fan
screen and in-cartemperature. Heating and
c o o l i n g functions are still controlled
automatically to give the required in-car
temperature. Pin 8 and 26 at the ECM are
earthed through the switch to give the
required in-car temperature.
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Figure 4.
Key to Fig. 4
1. AC signal Pin 26 ECM
2. M A N signal Pin 19 ECM
3. REC signal Pin 9 ECM
4. DEM signal Pin 8 ECM
5. Earth-ground Pin 1 ECM
6. Earth-ground Pin 1 ECM
7. AC signal Pin 26 ECM
8. ECO signal Pin 23 ECM
A ECO
B AC
C M A N
D Re-circulation
E DEM
8-22
May 1996