1997 ASTON MARTIN DB7 torque

Air Conditioning
System Checking with the Manifold Gauge Set D'^?
Purging the Test Hoses

1.
With the manifold test set attached to the system.

2.
Purge the high pressure test hose by cracking open
the high pressure side hand valve on the manifold
gauge set for 3 to 5 seconds. This allows the system
refrigerant to purge the air from the test hose and
discharge through the manifold centre test hose.
Immediately cl ose the high pressure side hand

valve.

3. Purge the low pressure test hose in the same manner
by cracking open the low pressure side hand valve
manifold gauge
set
for 3 to 5 seconds, then close the
hand valve.
Stabilising the System
The manifold gauge set is now attached to the
system and the test hoses purged of air. With both
hand valves closed, the system must be operated
for a few minutes to stabilise all pressures and
temperatures throughout the system in order to
obtain accurate test gauge readings.
Proceed as follows:

1.
Place all test hoses, gauge set and other equipment
away from all engine moving parts. Also keep the
hoses from touching the hot engine manifold.

2.
Start the engine and adjust engine speed to fast idle
3. Turn on the air conditioning and set for maximum
cooling with blower fans on high speed

4.
Open the car doors and/or windows (to quickly
eliminate car interior heat).
5. Operate the system under these conditions for 5 to
10 minutes to stabilise the system ready for testing.
6. Check the system for full refrigerant by noting the
sightglass indications. Some refrigerant loss occurs
over a period of time.
Note: The air conditioning
system
must contain a full
refrigerant
charge
before an accurate
system
check can
be
made.
An insufficient
charge
is indicated by
a stream

of
bubbles
or
foam.
If
the
refrigerant charge is low, the

system
must
be
fullydischarged into
a
refrigerant recovery
station and recharged with the correct weight of refrigerant
82.30.08. Do not top up a
system
with refrigerant.
Leak Test
A high proportion of ail air conditioning work
consists of locating and repairing leaks.
Many leaks are located at connections and are
caused by vibration. They may only require the re-
tightening of a connection or clamp.
Occasionally a hose rubs on a structural part of the
vehicle and creates a leak, or a hose deteriorates
which will require a replacement.
The specified maximum leakage rate at each fitting
is 0.5 kg of R 134a in 40 years and a leak detector
capable of operating to this accuracy must be

provided.
To check place the leak detector probe at
the lowest pointofeach joint, pausefortwo seconds.
Do not wave the probe about as refrigerant is
heavier than air and flows to the lowest point. If a
leak is greater than 0-5 kg in forty years is detected
identify the leak point for rectification.
Check that the leaking fitting has been tightened to
the correct torque. If the torque is low, rectify and
repeat leak test. If the torque is satisfactory,
depressurise the system, dismantle the leaking
connection and check the quality of the fitting.
If the fitting is satisfactory, clean and reassemble
after applying a thin film of refrigerant to the seat of
aflarefitting, ora newoiled "O" ring to an "O" ring

fitting.

Tighten to the correct torque.
Charge the system with 200 g of El 34A and leak test
the rectified system. If the system is satisfactory,
depressurise, evacuate and recharge the system.
If the system is unsatisfactory, i.e. leakage greater
than 0.5 kg in forty years, depressurise and replace
the leaking assembly.
8-40 May 1996

^?
Air Conditioning
Torque Settings / Depressurising the System
Torque Levels for the Hose Connections
COMPONENT TORQUE Nm
Evaporator Hose
Hose to Expansion Valve 32.0 ± 4.0
Hose to Compressor 34.0 ± 2.0
Condenser Hose
Hose to Compressor 34.0 ± 2.0
Hose to Compressor 25.0 ± 4.0
Condenser Pipe
Pipe to Drier Bottle 6.0 ± 1.5
Evaporator Pipe
Pipe to Expansion Valve 16.0 ± 1.5
Air Conditioning Procedures
Depressurising
Note:
Observe
all
safety
precautions and do not smoke
while carrying out the following
procedures.

1.
With the engine switched off, remove the protective
caps from the schraeder valves.

2.
Ensure the manifold gauge set hand valves are in
the closed position, then by using the access valve
core remover connect the manifold gauge set to the
system with the red hose to the high pressure side
and the blue hose to the low pressure side.
3. Screw out the valve core to allow the refrigerant to
flow.

4.
Place the centre hose of the manifold set into a
suitable container.
5. Slowly open the high or low side manifold hand
valve and adjust the valve for a smooth refrigerant
flow. Watch the refrigerant for any signsof escaping
oil and adjust the hand valve to prevent any oil

escaping.

6. If oil islostduringthedischarge,thecompressoroil
level must be checked and if necessary topped up.
7. As the discharge rate slows down, open the other
manifold hand valve so that refrigerant flows from
both high and low pressure sides of the system.
8. Constantly adjust the hand valves to ensure that oil
does not flow. When a zero reading is shown on
both high and low pressure gauges the system is
discharged.
8. Close both manifold hand valves.
Recovering Refrigerant
Caution: The
Recovery-Recycle-Recharging
equipment

has
special fittings to avoid
cross
contamination with
R-

12
systems.
Do not attempt to adapt
this
unit for
R-12
as
system
failure will
result.

Warning: Follow the safety procedures
as
defined at the
beginning of the section.
Caution: The unit's overfill limitation mechanism has

been
calibrated specifically for
use
with
the 50
lb.
(23 Kg)

refillable refrigerant
tank.

As the refrigerant is recovered it is passed through
an oil separator and
a
filter drier before it is allowed
to enter the refrigerant tank. When it is dry the
moisture indicator turns green.
May 1996 8-47

^2?
Air Conditioning
System Recharging / Compressor Oil Check
Recharging the System

1.
Open the high side valve on the unit control panel.
If the messages PROGRAM and CHARGE are not
displayed press the CHG key to enter PROGRAM

mode.

2.
Key in the amount of refrigerant needed to recharge
the system and press ENTER.
3. Press the CHG key; the message AUTOMATIC and
the entered amount of refrigerant wi
11
be displayed.
The display counts down to zero as the charging
process proceeds. When the charging is complete
the message CPL is displayed.
If the refrigerant transfer is too slow the charging
unit emits a signal. If the message CHECK
REFRIGERANT is not displayed, close the high side

valve,
open the low side valve and start the air
conditioning system to pull the remainder of the
charge into the system.
If the refrigerant transfer will not complete and the
message CHECK REFRIGERANT is displayed, press
the HOLD/CONT key to interrupt the cycle then
reset the unit by pressing the RESET key. Recover
the refrigerant already charged into the system by
following the procedure for recovering the
refrigerant, add new refrigerant to the tank and
return to Step 1 to recharge the system.

4.
If the air conditioning system is not running start it
and let it run until the gauge pressure readings
stabilize (compare the gauge readings with the
system manufacturer's specifications).
Note:
Ensure
that the
readings
are accurate by closing
both the high and low side
valves
on the unit's control
panel.
5. Check the evaporator outlet temperature to make
sure that the air conditioning system is operating
properly (refer to the system manufacturer's
specifications for the proper temperature).
Compressor Oil Checic
Data
Special Tools
Sanden oil dipstick JD 149
Torque Figures
Oil filler plug 8-12 Nm
Procedure
Whenever a component has been replaced in the
refrigerator system or there is an obvious oil leak, the
following procedure should be carried out.
A Sanden oil dipstick and angle gauge are required in
order to carry out the check.

1.
Run the compressor for 10 minutes at engine idle

speed.

2.
Depressurise the system.
3. Lay the angle gauge across the flat surfaces of the
two front mounting lobes. Centre the bubble and
note the mounting angle.

4.
Remove the compressor from the vehicle.
3. Remove the plug from the oil filler hole
(1
Fig. 1).

4.
Rotate the counter weight (3 Fig. 1) on the front of
theclutchtoallowthedipstick(2 Fig. 1)to penetrate
to its fullest extent.
Figure 1.
5. Insert the dipstick to its stop position (4 Fig. 1). The
point of dipstick angle should be facing left.
6. Removethedipstickandchecktheoil levelagainst
the figures quoted in the chart below.
May 1996 8-49

Air Conditioning
Compressor Oil Check ^^?
7.
Mounting
Degrees
0°
10°
20°
30°
40°
50°
60°
90°
Angle Acceptable
Increments
3-5
4-6
5-7
6-8
7-9
8-10
9-11
10-12
If the level indicated on the dipstick does not match
the increments given in the table for a particular
mounting angle, add or subtract oil to the midpoint

value.

Ensure that the "O" ring seal and seat are clean.
Coat the seal with compressor oil and refit the oil
filler
plug.

Torque tighten the plug to 8-12 Nm. Do not over
tighten the plug to stop a leak. If necessary, remove
the plug and fit a new oil
seal.

9. Refit the compressor.

10.
Recharge the system with refrigerant.
8-50 May 1996

Air Conditioning Repair Procedures

Field Coil Renewal
/
Gasket Kit Renewal ffi^e^'^^
8.1.02.1 Field Coil Renewal 8.1.03.1 Renew Gasket
Kit

Procedure

1.
Open
the
bonnet
and fit a
wing cover.

2.
Depressurise
the air
conditioning system.
3. Remove
the
compressor.

4.
Remove
the
compressor drive clutch.
5. Remove
the
compressor pulley.
6. Slacken
the
field coil wire clamp screw
(Fig.
1) and

release
the
wire from
the
clamp.

10.

Remove
the
field coil retaining snap ring
and

detach
the
field
coil.

Clean
the
mating face
of the
compressor with
a

cloth moistened with
an
approved cleaning
fluid.

Position
the new
field coil
on the
compressor
and

fit
the
retaining snap
ring.

Route
the
wire
to the
compressor
and fit the
wire
clamp, tighten
the
securing screw.

11.
Fit the
compressor pulley.

12.
Fit the
compressor drive clutch.

13.
Fit the
compressor.

14.
Recharge
the air
conditioning system.

15.
Remove
the
wing cover
and
close
the
bonnet.
Data
Torque Figures
Cylinder head bolts 29.83
to 33.9 Nm.

Procedure

1.
Open
the
bonnet
and fit a
wing cover.

2.
Depressurise
the air
conditioning system.
3. Remove
the
compressor.

4.
Position
the
compressor
in a
vice, tighten
the
vice
onto
the
compressor body lugs.
5. Remove the outlet port blanking plate securing bolt
and detach
the
plate.
6. Remove
and
discard
the 'O'
ring seals from
the

outlet port.
7. Remove
the
compressor cylinder head securing

bolts,
detach
the
cylinder head.
8. Detach
the
valve plate from
the
compressor.
9. Remove
the
gaskets from
the
compressor.

10.
Remove
all
traces
of
gasket material from
the

mating surfaces
of the
cylinder head, valve plate
and cylinder block.
Figure
1.

11.
Position
new
gaskets (Fig.
1 -1
and 3) on the
valve
plate
(Fig. 1-2) and
then place
it on the
cylinder
block.
8-52 May
1996

ES3^^
Air Conditioning Repair Procedures
Valve Plate Renewal

Figure
2.

12.
Position the cylinder head (Fig. 2-1) on the cylinder
block (Fig. 2-2), fit and tighten the securing bolts in
the sequence shown in Fig. 3.
8.1.04.1 Valve Plate Renewal
Data
Torque Figures
Cylinder head bolts 29.83 - 33.9 Nm
Procedure

1.
Open the bonnet and fit a wing cover.

2.
Depressurise the air conditioning system.
3. Remove the compressor.

4.
Position the compressor in a vice, tighten the vice
onto the compressor body lugs.
5. Remove the outlet port blanking plate securing bolt
and detach the plate.
6. Remove the 'O' ring seals from the compressor
outlet port.
figure 3.

13.
Fit new 'O' ring seals in the compressor outlet port,
position the outlet port blanking plate and fit and
tighten the securing bolt.

14.
Check and top up compressor oil

15.
Refit the compressor.

16.
Recharge the air conditioning system.
Figure 1.
7. Removethecylinder head securing boltsand detach
the cylinder head (Fig. 1-1) from the cylinder block.
8. Remove valve plate
(Fig.
1
-2) from the compressor.
9. Remove all traces of gasket material from the
mati
ng
surfaces of the cy
I
i nder
head
and compressor.

10.
Apply clean refrigerant oil to the gaskets and then
position them on the valve plate.
May 1996 8-53

^
The Aston Martin Lagonda Diagnostic System
Users Guide
Signal Description
lACDTCY Idle Air Control Duty Cycle (% open)
lAT Intake Air Temperature - °C or raw input counts
lAT STAT Air Temperature - Temperature sensor failure
lAT-V Intake Air Temperature - Volts or raw counts
IGN Desired Ignition Timing - ° BTDC
INDS Input from manual lever position sensor (counts)
IPWA Injector Pulse Width in mS- Bank A (Cylinders
1
-3)
IPWB Injector Pulse Width in mS- Bank B (Cylinders 4-6)
LAMSE1 Current Short Term Fuel Trim 1, adjustment from stoich - (% of range)
LAMSE2 Current Short Term Fuel Trim 2, adjustment from stoich - (% of range)
LFC Low Speed Fan Status
LOOP Fuel Control -1 = Open Loop, 0 = Closed Loop
MAF MAX Maximum Mass Air Flow signal during normal running
MAF Raw MAF sensor output (A/D counts)
MAF STAT Mass Air Flow Meter - MAF sensor failure
MIL Mali Indicator Lamp Status -1 = Lamp On
Mis HI Cumulative misfires detected by misfire test (Hi bit).
Mis LO Cumulative misfires detected by misfire test (Lo bit).
Mis nc HI Cumulative misfires detected by a misfire test (Hi bit).
Mis nc LO Cumulative misfires detected by a misfire test.
Misi HI Cumulative misfires detected by cylinder
1
misfire test (Hi bit).
Misi LO Cumulative misfires detected by cylinder
1
misfire test (Lo bit).
Mis2 HI Cumulative misfires detected by cylinder 2 misfire test (Hi bit).
Mis2 LO Cumulative misfires detected by cylinder 2 misfire test (Lo bit).
Mis3 HI Cumulative misfires detected by cylinder 3 misfire test (Hi bit).
Mis3 LO Cumulative misfires detected by cylinder 3 misfire test (Lo bit).
Mis4 HI Cumulative misfires detected by cylinder 4 misfire test (Hi bit).
Mis4 LO Cumulative misfires detected by cylinder 4 misfire test (Lo bit).
Mis5 HI Cumulative misfires detected by cylinder 5 misfire test (Hi bit).
Mis5 LO Cumulative misfires detected by cylinder 5 misfire test (Lo bit).
Mis6 HI Cumulative misfires detected by cylinder 6 misfire test (Hi bit).
Mis6 LO Cumulative misfires detected by cylinder 6 misfire test (Lo bit).
MISF Misfire Monitor - 1 = Currently misfiring
ODCODES Total number of on-demand codes currently stored.
PGM CVS DC Purge Management Duty Cycle (% on)
PIP Profile ignition Pick-Up - PIP input level
PNP Park Neutral Position Switch
R-BIAS1 Rear bias trim (Bank 1, cylinders
1
-3)
R-BIAS2 Rear bias trim (Bank 2, cylinders 4-6)
RATCH Lowest TP reading during driving
TP MAX Maximum Throttle Potentiometer signal during normal running
TP STAT Throttle Position Sensor - TP sensor failure
TP Throttle Potentiometer - Volts or counts
TPR-V Raw counts from sensor
TQ-NET Net torque into the torque convertor
TRIP OBDII Drive Cycle Complete (except cat monitor) - 1 = Trip completed
TRIPCNT Number of Completed OBDII Trips
VS MAX Maximum Vehicle Speed signal during normal running
VS STAT Vehicle Speed Sensor mode flag
VS Vehicle Speed - MPH
WAC Wide Open Throttle A/C Cut-Off -1 = High (WOT Relay)
September 1996 9-37

The Aston Martin Lagonda Diagnostic System
Users Guide ^=2?
Transmission Diagnostics
Automatic transmission DB7s are fitted with a GM4L80-
E gearbox electronically controlled by a Transmission
Control Unit (TCM)
The TCM is mounted on the rear left wheel
arch.
It may be
electronically accessed from the upper diagnostic socket.
The TCM continuously monitors requests made by the
driver via the gear selector, throttle pedal, mode switch,
etc. This data is used in conjunction with speed input from
the transmission unit to calculate the optimum shift points
undercurrentconditions.Shiftpressureand ignition retard
are also controlled from this data to enhance shift quality
and reduce transmission wear.
TheTCM also detects faults within the transmission system
and stores the relevant fault codes for later analysis.
Gearshifts are controlled by two solenoid valves and a
pressure regulator within the transmission valve block
assembly.
If a serious fault occurs, the TCM removes all electrical
power from these valves and the transmission defaults to
a 'limp home' condition. In this state, only mechanical
selection of either reverse or second gear is available.
Gearshift Timing
Inputs from the performance mode switch (Sport, Normal
or 1st Gear Inhibit) and the throttle position sensor are
used to modify transmission gearshift operation
as
required
by the driver.
Sport mode raises the roadspeed at which gearshifts occur
enabling higher acceleration rates for the vehicle.
1st gear inhibit prevents engagement of first gear to reduce
the risk of wheel slip in icy conditions.
The throttle position sensor signal is continuously
monitored by the TCM to detect a rapid throttle opening.
If the throttle position sensor signal rises rapidly to above
4.5 volts, a 'Kickdown' condition is initiated. In this

condition,
upshifts are delayed to higher road speeds to
provide the higher acceleration required for overtaking
etc.
TCM - PCM Communication
The interface between TCM and PCM allows continuous
exchange of the primary data required to appropriately
control the gearshifts required during driving under
a
wide
range of conditions.
Powertrain
Control
Module
^.. ^
Warm-Up Signal
Throttle Pot Output
Torque Reduction Request
^ •- -^ Transmission
Control
Module
Warm-Up
The Warm-Up signal is sent from the TCM to the PCM and
is used to detect when the transmission reaches normal
operating temperature of approximately 100°C (212"'F).
As this temperature is reached, the modified gearshift
timing required with a cold gearbox may be abandoned in
favour of the standard timing for a warm gearbox.
Throttle Pot Output
The ThrottlePot Output signal is sent from the PCM to the

TCM.
The TCM can then use this information to control
shift timing in relation to the power demanded by the
driver.
Torque Reduction Request
The Torque Reduction Requestsignai
is
sent from the TCM
to the PCM. it is used to temporarily retard the ignition
timing during gear shifts to improve shift quality. When the
gearshift is completed, ignition timing will be returned to

normal.

9-40 September 1996