1997 ASTON MARTIN DB7 refrigerant type

Body and Trim //-->> ^izz^^ ' ^ ^
Body Repair ' —^^ '-^ >^-/
Body Repair
Introduction
This section contains information for the body repair and rectification of the vehicle. Wherever possible the vehicle
must be returned to its original manufactured condition. Following repair the vehicle must be fully checked and, if
necessary, the braking system and steering must be fully reset.
Health and Safety
Ensure that the correct working practices are established before beginning work.
Observe that the correct working practices are followed whether they be legislative or common sense.
Be aware of the potential risks of using materials used in the manufacture and repair of vehicles and take the
appropriate precautions.
Warning: Make sure that the working practices for the air conditioning
system
are followed: do not vent the refrigerant
directly into the atmosphere and always use the approved recovery/recycle /recharge equipment, always wear
suitable protective garments to prevent injury to the eyes and the skin.
Potential Risks
Paint
If the organic solvents, contained in paints, are inhaled for any length of time damage can be caused to the liver,
kidneys, respiratory tract and the digestive system.
Prolonged exposure to isocyanates can cause lung sensitisation and asthma-like symtoms can develop with
subsequent re-exposure to even low concentrations.
Solvent inhilation can cause dizziness or loss of consciousness.
Inhilation of spray dust and sanding debris can cause lung damage.
Paint activatorsand additives will damage the eyesor can cause dermatitis if allowed to splash and come into contact
with these areas. Peroxide and acid catalysts can cause burns.
Applied heat
There is considerable risk of damage to the eyes and skin when welding or flame cutting.
Fire is a serious danger as many materials and fluids in the vehicle are inflammable.
Toxic and dangerous fumes can be liberated when the following are subjected to heat; expanded foam, corrosion

protection,
adhesive and sealing compounds,
trim,
seat material and paints that contain isocyanates.
When heated to
a
temperature of 300°C, polyu rethane based compounds can
1
iberate small quantities of isocyanate.
Many types of nitrogen containing chemicals may be liberated as breakdown products, these chemicals can
contain isocyanates, oxides of nitrogen and hydrogen cyanide.
Potentially toxic or asphyxiant fumes and gases are produced by welding, for example; zinc oxide with zinc coated
panels and ozone gas from the MIC process.
Metal repair
There is considerable risk of damage to the eyes, ears and skin when metal cutting, forming and dressing is being
carried out.
Soldering may be hazardous because of heat generated fumes and skin contact with the materials.
7-2 May 1996

Em^^^?
Air Conditioning
General Description
General Description
Specifications
Refrigerant
Designation
Refrigerant R134A

(HFCUAA)

Compressor
Type
&
model
SD-7H15
Charge weight
1050g±50g
Configuration
7 cylinder
Compressor Lubricants
Designation
Polyalkylene glycol
(PAG)

Standard
for
Recovery, Recharge
and
Recycle Equipment,
System Capacity
120-150
ml

Manufacturer and Type
ICI Klea
or
equivalent

Manufacturer

Sanden
155 cm^
per
revolution
Manufacturer and Type
Sanden SP
20

Feature

Recovery rate
Cleaning capability
Oil separator
Vacuum pump
Filter

Charge

Hoses
Charge pressure
Compressor Belt Tension
Type
Vee belt
Burroughs method
Clavis method
Requirement

0.014-0.062
mVmin.
(1.36 kg in 20
minutes)
15
ppm
moisture; 4000
ppm oil; 330 ppm
non-condensable gases
in air

With hermetic compressor and automatic
oil
return
2 stage
0.07
-0.127 mVmin.
Replaceable with moisture indicator
Selectable charge weight and automatic delivery
Dedicated Refrigerant R134A port connections.
Heating element
to
increase pressure
Condition and range
All figures apply
to a
cold belt.
New belt
578 to 623 N

If tension
is
below
356 N,
reset
at 512 to 534 N

New belt
147 to 153 Hz

If tension
is
below
110 Hz,
reset
at 132 to 138 Hz

Note:
The
tension
is
measured
midway between the
compressor
and crankshaft pulleys. For a new
belt,
rotate engine three
revolutions minimum and then re-check the tension.

May 1996
8-5

Air Conditioning //~-->> ^/zz:^^ • ^ ^
General Svstem Procedures ' —"^ ^ '^ General System Procedures
From the condenser the liquid passes into the Receiver-Drier which has three functions:
• Storage vessel for varying system refrigerant demands.
• Filter to remove system contaminants.
• Moisture removal via the desiccant.
With the passage through the receiver-drier completed the, still high pressure liquid refrigerant, enters the Expansion
Valve where it is metered through a controlled orifice which has the effect of reducing the pressure and temperature.
The refrigerant, now in a cold atomised state, flows into the Evaporator and cools the air which is passing through
the matrix.
As heat is absorbed by the refrigerant it once again changes state, into a vapour, and returns to the compressor for
the cycle to be repeated (Fig. 5).
There is an automatic safety valve incorporated in the compressor which operates should the system pressure be
in excess of
41
bar. The valve re-seats when the pressure drops below 35 bar.
Note: The division of HIGH and LOW side is simply the
system pressure
differential created by the
compressor
discharge

(pressure),
suction
(inlet)
ports and
the
relative inlet and outlet
ports
of the
expansion
valve.
This
differential is critical to
system

fault
diagnosis
and efficiency checks.
System Protection
The trinary pressure switch, located in the liquid line, cuts electrical power to the compressor clutch if the system
pressure is outside of the range of 2 Bar
(1
st Function) to 27 Bar (2nd Function). The third function is to switch on
the cooling fans when pressure exceeds 20 bar.
General System Procedures
Leak Test
Faults associated with low refrigerant charge weight and low pressure may be caused by leakage. Leaks traced to
mechanical connections may be caused by torque relaxation or joint face contamination. Evidence of oil around
such areas is an indicator of leakage. When checking for non visible leaks use only a dedicated Refrigerant El 34A
electronic analyser and apply the probe all round the joint connection. Should a leak be traced to a joint, check that
the fixing is secured to the correct tightening torque before any other action is taken.
Do not forget to check the compressor shaft seal and evaporator.
Note: Never
use
a dedicated
CFC 12
or
naiced
flame type
analyser.

Charge Recovery (System Depressurisation)
The process of refrigerant recovery depends on the basic characteristics of your chosen recovery-recycle-recharge
equipment, therefore, follow the manufacturers instructions carefully. Remember that compressor oil may be drawn
out of the system by this process, take note of the quantity recovered so that it may be replaced.
CAUTION: Observe all relevant safety requirements.
• Do not vent refrigerant directly to atmosphere and always use approved recovery-recycle-recharge
equipment.
• Wear suitable eye and skin protection.
• Do not mix the refrigerant with CFC 12.
• Take note of the amount of recovered refrigerant, it indica
tes the
state of the
system
and
thus the
magnitude
of any problem.
8-12 May 1996

Air Conditioning
Manifold Gauge Set 5=2?
Manifold Gauge Set
The manifold gauge set is a most important tool for
fault diagnosis and system efficiency assessment.
The relationship to each other of HIGH and LOW
pressures and their correlation to AMBIENT and
EVAPORATOR temperatures must be compared to
determine system status. Because oi the heavy
reliance upon this piece of equipment for service
diagnosis, ensure that the gauges are calibrated
regularly and the equipment is treated with care.
BLUE LOW SIDE RED HIGH SIDE
LOW

m
m

Manifold.

The manifold is designed to control refrigerant
flow. When connected into the system, pressure is
registered on both gauges at all times. During
system tests both the high and low side hand valves
should be closed (rotate clockwise to seat the
valves). The hand valves isolate the low and the
high sides from the centre (service) hose.
Low Side Pressure Gauge.
This compound gauge
is
designed to register positive
and negative pressure and may be calibrated as
follows:
• Full Scale Deflection - 0 to 24 bar pressure
in a clockwise direction
• Otol bar FSD negative pressure in a counter
clockwise direction.
High Side Pressure Gauge.
This pressure gauge may be calibrated from 0 to 34
bar FSD inaclockwisedirection. Depending on the
manufacturer, this gauge may also be of the
compound type.
Figure 1
The gauge set (Fig. 1) consists of a manifold fitted
with:

1 Low side service hose - BLUE.
2 Low Side hand valve - BLUE.
3 Low pressure compound gauge - BLUE.
4 High pressure gauge- RED.
5 High Side hand valve - RED.
6 High side service hose - RED.
7 System service hose - NEUTRAL COLOUR
(commonly yellow).
8-38 May 1996

^2?
Air Conditioning
System Checking with the Manifold Gauge Set
Compressor Malfunction
Complaint.
Cooling is not adequate.
Condenser Malfunction or System Overcharge
Complaint.
Little or no cooling. Overheating of the engine may
also be noted.
BLUE LOW SIDE

BLUE
LOW SIDE BED HICH SIDE
Condition

1.
The low side gauge reading is too
high.

2.
The high gauge reading is too low.
3. The sight glass is free of bubbles and the system is
fully charged.

4.
The discharge air from the evaporator is not
sufficiently
cool.

Diagnosis.
Internal leak in the compressor.
Correction.

1.
Depressurise the system.

2.
Renew the compressor and the drier bottle.
3. Evacuate the system using a vacuum pump.

4.
Charge the system with new refrigerant.
5. Operate the system and check the performance.
HIGH
Condition.

1.
The low side gauge reading excessively
high.

2.
The high side gauge reading is also excessively

high.

3. Bubbles may appear occasionally in the sight glass
and the liquid line to the evaporator is very hot.

4.
The discharge air from the evaporator is warm.
Diagnosis.
The condenser not operating correctly through lack
of cooling caused by too high a high side pressure.
The system may have either
a
normal or overcharge
of refrigerant.
Correction.

1.
Checkthecompressordrivebeltforcorrecttension.

2.
Check the condenser for clogged air passages
preventing air flow through the condenser.
3. Inspect the condenser mounting for correct radiator
clearance.

4.
Check for correct fan operation.
5. Check the coolant pressure capfor correct type and

operation.

May 1996 8-43