1997 ASTON MARTIN DB7 Workshop Manual

Air Conditioning Repair Procedures
Blower Assembly Renewal o^s^-^?

12.
Disconnect the vacuum pipe from the flap actuator

(Fig.
1-4).

13.
Open the re-circulation flap in the base of the
blower assembly and fit a wedge to retain it in the
open position (Fig. 1-5).

14.
Remove the bolts securing the blower assembly
and ease the blower unit from its location (Fig.
1
-6).

15.
Remove the tape securing the ducting to the
assembly and remove the ducting (Fig.
1
-7).
Note: To remove the blower motor
assembly
from the
vehicle,
the
lower flap must be opened to allow the upper
flap to
disengage
from the upper body
aperture.

8.2.10.1 Blower Assembly Driver/
Passenger Side Overhaul

Note:
Blower
assemblies
under warranty must not be
dismantled.

1.
Remove the three selftapping screws
(Fig.
1-1) from
the air intake casing.
Figure 7.

2.
Part the air intake casing (Fig.
1
-2) from the motor
assembly (Fig. 1-2) and disconnect the electrical
connections at the lucar connectors (Fig.
1
-4).
Note: Mark the position of the
various components
with
paint or
a
scriber.
This
facilitates
re-assembly.

3. One lucar connector has a raised projection which
matches the aperture in the motor casing to ensure
that the connections are replaced correctly and that
the rotation of the motor is unaffected.

4.
Remove the bolts securing the motor mounting
bracket to the fan housing (Fig. 1-5).
5. Remove the motor and fan assembly from the fan

housing.

6. Remove the mounting bracket from the motor.
7. Using appropriate Allen key, remove the impellor
fan from the spindle.
Re-assembling

1.
Refit the fan to the motor and secure it to the
spindle.

2.
Refit the mounting bracket tot he motor.
3. Locate the fan and mounting assembly into the fan

housing.

8-60 May 1996

o --^ ^^?
Air Conditioning Repair Procedures
Blower Motor High Speed Relay Renewal
6.
7.
8.
Place the flap box assembly to the fan housing and
reconnect the electrical connections.
Fit and tighten the screws securing the flap box to
the housing.
Raise the re-circulation flap, fit and tighten the
remaining screw.
Refit the blower motor assembly.
Reconnect the battery earth-ground
lead.

8.2.11.1
Blower Motor
High Speed
Relay
Renewal

1.
Remove the blower motor assembly complete.
Figure 7.

2.
Open the flap for access.
3. Using a suitable tool remove the relay from the
blower assembly (Fig.
1
-1).

4.
Fit a
new relay
and
refit the blower motor assembly.
May 1996 8-61

Air Conditioning Repair Procedures
Water Temperature Switch/Heater Matrix Renew •=2?
8.2.12.1 Water Temperature Switch
Renewal

1.
Disconnect the battery earth
lead.

2.
Un-clip and remove the left hand underscuttle

casing.

Figure.
3. Note and disconnect the feed wires from the switch

(Fig.
1-1).

4.
Displace and remove the switch from the water

pipe.

5. Fitting a new switch is the reversal of the removal
procedure.
8.2.13.1 Heater Matrix Renewal

1.
Disconnect the battery earth
lead.

2.
Remove the left hand underscuttle panel.
3. (On right hand cars) Remove the glove box
assembly.
3. (On left hand cars) Remove the instrument pack
and surround
trim,
steering column and mounting
bracket.

4.
Drain the coolant into a suitable container.
5. Remove the matrix cover panel securing screws.
6. Removethe rear
panel,
displacethefront panel and
foam seal for access.
7. Place rag in position.
8. Remove screws securing the feed pipe and
disconnect the pipe from the matrix.
9. Remove and discard the gasket.

10.
Remove the screws securing the feed pipe and
disconnect the pipe from the matrix.

11.
Remove and discard the gasket.

12.
Disconnectthewatertemperatureswitchfeedwires.

13.
Remove the foam pad from the pipes.

14.
Remove the front panel from the unit.

15.
Undo the heater hose matrix pipe hose clips and
disconnect the hoses from the pipes.

16.
Reposition the pipes from the matrix.

1
7. Remove the matrix from the air conditioning unit.

18.
Fitting a new matrix is the reversal of the removal
procedure.

19.
Ensure that new gaskets are fitted.
8-62 May 1996

^>
Air Conditioning Repair Procedures
Electronic Control Module/Vacuum Solenoid Renewal
8.2.14.1 Electronic Control Module
Renew
8.3.01.1 Vacuum System Solenoid
Renewal

1.
Disconnect the battery earth
lead.

2.
Remove the right hand underscuttle casing.
3. (On left hand cars) Removethe glove box assembly.
3. (On right hand cars) Remove the instrument pack
and surround
trim.

4.
Disconnect the earth wire and three block
connectors from the control module (Fig.
1
-2).
5. Remove the securing screws and module from the
air conditioning unit (Fig. 1-1).
Fitting a new module
is
the reversal of the removal
procedure.
The flaps in the cabin air distribution vents and the
water valve in the pipe line from the engine coolant
system to the heater matrix are all operated by
vacuumactuators.The vacuumfor these issupplied
by four solenoids mounted in a manifold pack
located behind the front left hand footwell outlet.
Failureof a solenoid will require replacement of the
manifold pack.
Procedure

1.
Disconnect the battery earth
lead.

2.
Remove the following:
• glove box and lid
• facia trim (walnut strip)
• radio and ashtray
• centre console switch assembly
• left hand underscuttle casing/knee bolster
Detai
Is
ofthe above operations can be found in the
trim and the electrical sections.

2.
Remove thefixings joining the centre console to the

facia.
This allows the front of the console to be
repositioned for access.
3. Disconnect the ducting from the left hand footwell
outlet.

4.
Remove the two plastic fixings that secure the
slotted footwel
I
outlet and
si
ide the outlet out ofthe
unit.
7. Cut the tie strap holding the vacuum lines and
electrical harness to the underside of the air
conditioning unit.
8. Remove the screws that secure the manifold pack
to the underside of the air conditioning unit and
slide out the plate complete with the manifold
pack.

10.
To fit a new manifold pack reverse the steps for the

removal.

May 1996 8-63

Air Conditioning Repair Procedures
O ^?
8-64 May 1996

Air Conditioning
Air-Conditioning Diagnostics
The Air Conditioning System Diagnostics
The air-conditioning control module (A/CCM) is located at the right end of the air-conditioning unit.

A
digital microprocessor within the
A/CCM
receives
data
signals from
the
operator controlled
switches.
Comparison
of these signals with those returned from the system temperature sensor and feedback devices results in the
appropriate voltage changes necessary to vary: blower motor
speed,
flap positions and system solenoids to respond
to the drivers selected temperature demand.
The air from the two blower motors is passed through the evaporator matrix which, depending on the A/C mode

selected,
removes heat from the incoming air. Depending on the position of
the
two blend
flaps,
the cold air passes
either directly into the vehicle outlet vents, or is passed through the heater matrix to be reheated and then passed
to the vehicle outlet vents.
The amount of air passing through the heater matrix is infinitely variable depending on ambient temperature and
the temperature selected within the vehicle.
Air Conditioning Diagnostics
Cable Connections to the A/CCM
Cable Setup
Figure 1. PDU connections to the A/CCM

1.
Remove the right side underdash trim panel.

2.
Connect the VBA (0024) to the vehicle battery
3. Connect the PDU to the VBA (0024).

4.
Connect the VIA to the PDU using the VIA-PDU cable (0030).
5. Connect the AirCon Datalogger harness (0780) between the VIA Channel A and the Air-Conditioning Control
Module on the vehicle.
May 1996 8-65

Air Conditioning
Portable Diagnostic Unit - Signal Monitoring 3^^?
Air Conditioning Signal Monitoring
The following signals can be monitored using the PDU. The abbreviated name of the signal is shown on the PDU
display.
Display Name Full Signal Name
AMBTEMP Ambient temperature sensor
ARECIP Auto-Recirculation input
ARECOP Auto-Recirculation output
AUX+ Auxiliary battery positive
CLUREL Clutch relay drive output
CVSOL Centre vent solenoid
DEFSOL Defrost solenoid
DIFF Temperature differential
EVSEN Evaporator sensor
FANDEF Fanspeed defrost
FANHIG Fanspeed high
FAN LOW Fanspeed low
FANMED Fanspeed medium
FIVEV Five volt supply voltage
FORSERL Lower servo forward drive
FORSERU Upper servo forward drive
GND10 Ground voltage
GND2 Ground voltage
GND38 Ground voltage
GND45 Ground voltage
GND6 Ground voltage
HSREL High speed relay drive
ICSEN In-Car sensor
LBLOFB Left blower feedback voltage
LBLOWOP Left blower output voltage
LSERFB Lower servo feedback potentiometer
MPROBE Measurement probe
POWIN+ Switched power input
POWOP+ Power output
RBLOFB Right blower feedback voltage
RBLOWOP Right blower output voltage
REF Reference signal
REVSERL Lower servo reverse drive
REVSERU Upper servo reverse drive
TEMPDEM Temperature demand
USERFB Upper servo feedback potentiometer
WATSW Water switch
WATVAL Water valve
8-66 May 1996

^=2?
Air Conditioning
Portable Diagnostic Unit - Signal Definitions
ThefollowingsignalsaresupportedontheAir-ConditioningControlModule. For each signal. The signal name, mnemonic
and background information are detailed.
Ambient Temperature Sensor
(AMBTEMP)
Auto-Recircuiation Input
(ARECIP)
Auto-Recirculation Output
(ARECOP)
Auxiliary Battery Positive
(AUX+)
Clutch Relay Drive Output
(CLUREL)
A/CCM Pin 34 ref Pin 6
This sensor is located in the right hand blower motor. This signal is used to enable
the A/C system to compensate for changes in ambient air temperature. The output
to pin 34 is 2.732 volts at 0 degrees Celsius and changes by 0.01 volts for each
degree Celsius above or below zero.
A/CCM Pin 9 ref Pin 6
This is effectively an On/Off switch for the A/C system and forms part of the fan
control switch.
Switch Off - Pin 9 should be at ground
Switch On - Pin 9 should be at 10+ volts.
When pin 9 is at ground, pin 3 will be at 10+ volts causing the recirculation flaps
to open.
A/CCM Pin 3 ref Pin 6
This signal will cause the recirculation flaps to close. Operating conditions should

be:

A/C Off - 10+ volts at pin 3, flaps open.
Temp demand minimum - 10+ volts at pin 3, flaps open.
Defrost - 0 volts at pin 3, flaps closed.
Temp demand max - 0 volts at pin 3, flaps closed.
A/CCM Pin 1 ref Vehicle Battery -ve
This signal istheauxiliary supply to the A/CCM. Pin
1
should read battery voltage
if the ignition switch is in the auxiliary or ignition on positions. Pin
1
should read
0 volts when the ignition switch is in the Off position or in position III whilst
cranking the engine. Loss of this supply will cause total failureof the A/C system.
A/CCM Pin 20 ref Pin 6
This signal responds to the input at pin 5 (evaporator sensor). When pin 5 is
between 2.715 and 2.725 volts, pin 20 should read below 1 volt, and the
compressor clutch will be switched off. When pin 5 is between 2.735 and 2.745

volts,
pin 20 will rise to 10+ volts and the compressor will re-engage.
Centre Vent Solenoid
(CVSOL) A/CCM Pin 18 ref Pin 6
The centre vent solenoid controls the operation of the centre vent flap. The centre
vent will open to increase the cooling capabilities of the vehicle when cooling is

selected.
In all other conditions, the centre vent will be closed.
Solenoid energised: pin 18 should read 10+volts and the centre vent will be open.
Solenoid de-energised; pin 18 should read below 0.5 volts and the centre vent
should be closed.
May 1996 8-67