1997 ASTON MARTIN DB7 oil pressure

Air Conditioning
Compressors ^?
Evaporator
Figure 3.
Receiver-Drier
The receiver drier (Fig. 1) accepts high pressure
warm refrigerant liquid from the condenser and
del ivers it via an expansion valve to the evaporator.
It contains a quantity of molecular sieve desiccant
to remove moisture from the refrigerant, and
a
fi Iter
to removecontaminants.lt also
a
providesa reservoir
of refrigerant for the evaporator under varying
operating conditions.
The evaporator consists of a refrigerant coil mounted
in a series of thin fins to provide a maximum
amount of heat transfer in a minimum amount of

space.
It is housed in the air conditioning unit and
all air entering the system passes across its
coil.

The evaporator receives refrigerant from the
thermostatic expansion valve as a low pressure
cold atomised liquid. As this cold liquid passes
through the evaporator coils, it absorbs heat from
the surrounding air and changes into
a
low pressure
warm vapour.
Expansion Valve
The expansion valve is the dividing point between
the high and low pressure sides of the system. It
automatically meters high pressure, warm liquid
refrigerant via a metering orifice into the low
pressure, cold side of the evaporator matrix. The
valve senses outlet pipe temperature, inlet pipe
pressure and regulates the flow of refrigerant into
the evaporator to ensure that only vaporised
refrigerant appears at the outlet.
Figure 1.
8-36 May 1996

^?
Air Conditioning
Sanden Compressor SD7H15
Sanden Compressor SD7H15
The Sanden SD7H15 compressor
is a 7
cylinder
machine with
a
bore
of
29.3
mm (1.15 in) and a

stroke
of
32.8
mm (1.29
inches).
The displacement
per
revolution
is
155cc
(9.5

cubic inches).
The magnetic clutch
is
engineered with
the

compressor
as a
complete assembly resulting
in a

relatively small unit
of
lightweight construction.
The compressor may be mounted up to 90° from
its

upright position.
The compressor incorporates
a
lubrication system
which reduces the
oil
circulation ratio
to a
level
of

less than
2% at 1800 rpm.

An
oil
deflector
and
positive pressure differential
lubrication system promotes oiling
to the
cylinder

wall,
piston
rod
assemblies, main bearings
and

shaft
seal,
and
ensures that
oil
circulation
to the

refrigeration circuit
is
kept
to a
minimum.
The

compressor ischarged
with!
35 cc(4.6fluid ounces)
ofSunico NoSGSoil at the factory. Only this oil
or

oneoftheequivalentoilsdetailed below should
be

used.

Key

1.

2.

3.
4.
5.
6.
7.
8.

9.
10.

11.

12.
13.
14.
15.
16.

to Fig. 2.
Service port
Cylinder head
Hose connection
Anti-rotation gear
Oil filler plug
Planet plate
Clutch bearing
Electromagnetic clutch
Valve plate assembly
Cylinder and valve plate gasket
Cylinder block
Piston
Cam rotor
Needle thrust bearing
Front housing and 'O' ring
Shaft seal
Compressor Oils
Suni
CO
No 5GS
Texaco Capella E
Virginia Chemicals 500 Viscosity

13
14 15 16

Figure
2.

May
1996
8-37

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

=2?
Air Conditioning
System Checking with the Manifold Gauge Set
Pressure Temperature Relationship.
Note:
Pressures
shown are under exact conditions
(see
test
conditions) and
are
not
necessary
true for every
car

checked.
Ambient Temperature is given as the air
surrounding the
condenser
and
is
taken 5 cm in front of
the
condenser.

Test Conditions.
Use a large fan to substitute for normal ram air through the
condenser. Engine adjusted to fast idle speed.
All conditions equivalent to 30 m.p.h. or 48 km/h.
Ambient
Evaporator
Temp °C
16
18
21
24
27
29
32
35
38
41
43
46
49
High
Pressure
Gauge
Reading
Ibf/in2
95-115
105-125
115-125
130-150

1
50-170
165-185
175-195
185-205
210-230
230-250
250-270
265-285
280-310
Low
Pressure
Gauge
Reading
Ibf/in2
10
12
4
16
18
20
22
24
26
28
30
35
40
45
50
55
60
65
70
Ten
-16
-14
-12
-10
-8
-6
-5
-4
-3
-1
0
2
5
9
11
14
17
19
21
Normal operating ambient temperature range is:
-24 to 43°C.
Normal operating evaporator temperature range
is:-12toO°C.
Under normal running conditions system pressure
should be, as follows:
Lowside:1.05to2.10kgf/cm21.034to2.06bar15
to 30 ibf/in2
High side: 13.00 to 14.40 kgf/cm2 12.75 to 14.34
bar185to205lbf/in2
Manifold Gauge Set Check Procedures
Refrigerant Slightly Low.
Complaint.
Little or no cooling.

1.

2.

3.

4.

1.

2.

3.

4.

5.
6.
7.
BLUE LOW SIDE
KED
HIGH SIDE
Condition.
The low side gauge reading is too low.
The high side gauge reading is too low.
A stream of bubbles evident in the sight glass.
The discharge air from the evaporator only
slightly
cool.

Diagnosis.
The system low on refrigerant due to slight leak.
Correction.
Test the system for leaks.
Depressurise the system.
Repair the leaks, and if necessary renew hoses or

units.

Check the compressor oil level. The system may
have lost oil due to leakage.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
May 1996 8-41

Air Conditioning
System Checking with the Manifold Gauge Set [n::S3^^?
Refrigerant Excessively Low.
Complaint.
Cooling is not adequate.
Air In The System.
Complaint.
Cooling is not adequate.
BLU£ LOW SIDE SlUE LOW SIDE MD HIGH SIDE
5.
6.
7.

Condition.

1.
The low side gauge is reading very low.

2.
The high side gauge reading very low.
3. No bubbles or liquid evident in the sight glass.

4.
The discharge air from the evaporator is warm.
Diagnosis.
System refrigerant excessively low. Serious leak

indicated.

Correction.

1.
Test the system for leaks.
Note: Partially recharge the
system
before testing the

system
for
leaks
to
ensure that leak detection is
obtained.
Depressurise the system.
Repair the leaks, and if necessary renew hoses or

units.

Check the compressor oil level. The system may
have lost oil due to leakage.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
performance.

2.

3.

5.
6.
7.
8-42
Condition.
The low side gauge reading
is
constant and does not

drop.
The pressure should drop until the compressor
cycles (thermostat control)
The high side gauge reading is slightly high (or
slightly lower especially if a large fan is used to
substitute ram air).
The sight glass is free of bubbles or only shows an
occasional bubble.
Thedischarge air from theevaporator
is
only slightly

cool.

Diagnosis.
Non condensables present in the system. Air or
moisturepresent instead of afullrefrigerantcharge.
Correction.
Test the system for leaks. Test the compressor seal
area very carefully.
Depressurise the system. Repair the leaks, and if
necessary renew hoses or units.
Renew the drier bottle, probably water saturated .
Check the compressor oil level.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
May 1996

Air Conditioning
System Checking with the Manifold Gauge Set ffi:S5=27
After making the above checks operate the system
and check the performance. If the Condition is not

rectified.

1.
inspect the system for overcharge of refrigerant and
rectify as follows.
A. Discharge the system, until a stream of bubbles
appear in the sight glass and both gauge readings
drop to below normal.
B. Add new refrigerant until the bubbles disappear
and the pressures are normal. Then add 0.25 to 0.5

lb.
of additional refrigerant.

2.
Operate the system and check the performance.
If the gauge readings are still too
high.

3. Depressurise the system.
3. Removeand inspectthecondenserforoilclogging.
Clean and flush the condenser to ensure the free
passage refrigerant or renew the condenser.

4.
Renew the receiver-drier.
5. Evacuatethesystem using
a
vacuum pump Recharge
the system with new refrigerant. Operate the system
and check the performance
Moisture in the System
Complaint.
Cooling notadequateduringthe hot part of theday.
Note: Cooling may
be satisfactory
during
early
morning/

late evening
but
inadequate
during
the
hot part of
the
day.

BLUE LOW SIDE RED HIGH SIDE

1.

2.

3.

4.

5.
LOW
Condition.
The low side gauge reading normal but may drop
into vacuum during testing.
The high side gauge reading normal but drops
when the low side drops into vacuum. The sight
glass may show tiny bubbles.
The discharge air from the evaporator is cold but
becomes warm when the low side gauge drops into

vacuum.

Diagnosis.
Excessive moisture in the system.
Desiccant agent saturated with moisture which is
released during high temperatures. The moisture
collects and freezes in the expansion valve which
stops the refrigerant flow.
Correction.
Depressurise the system.
Renew the drier bottle.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
8-44 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

Air Conditioning
Refrigerant Recovery and Recycling ^=2?
Recovery Procedure
Hote:
Run the
air-conditioning
system
for
a
few
minutes
before starting the
recovery
procedure as
this will
enable

more refrigerant to be recovered. Turn the
system
off
before
starting
the procedure.

1.
Attach the red (high side) hose oftheunittothe high
side fitting of the system on the vehicle then fit the
blue (low side) fitting to the low side on the vehicle.
Note: Make sure that the Air conditioning
system
has
pressure in it before beginning the recovery
process;
if
there is no
system
pressure there is no refrigerant to

recover.
Also
make sure that the
oil
drain
valve
is
closed.

2. Open both the high and low side valves on the
control panel.
3. Open the red CAS (vapour) valve and the blue
LIQUID valve on the tank.

4.
Turn on the MAIN POWER switch.
5. Press the RECOVERY key on the key-pad. The
display shows that the unit in the RECOVER mode
and AUTOMATIC cycle. After the compressor starts
the display shows the weight of refrigerant being

recovered.
The compressor shuts off automatically
when the recovery is complete and the display
shows the message 'CPL' and the final weight of the
recovered refrigerant.
6. Wait for five minutes and watch the manifold
gauges for a rise above 0. If a rise occurs press the
HOLD/CONT key. Repeat as needed until the
system pressure holds for two minutes.
Note: Drain the oil
separator
after
each
job.
7. Slowly open the oil drain valve and drain the oil
into the oil catch bottle. When all the recovered oil
has completely drained close the valve.
8. Replace oil lost during the recovery procedure by
measuringthe amount of oil inthe catch bottle and
adding the same amount of new oil to the system.
Note:
Dispose
of the
recovered
oil in an approved way.
9. When the recovery tank is full the compressor is
shut off and the display shows the message FULL.
Evacuating and Recycling the Refrigerant

1.
Open the red (high side) and the blue (low side)
valves on the unit and open the red GAS (vapour)
valve and the blue LIQUID valve on the tank.

2.
Enter the required time using the key-pad, press
enter,thedisplayshowstheenteredtime in minutes.
3. Start the vacuum pump by pressing the VACUUM
KEY again. The recycling process begins
approximately five seconds after the vacuum pump
starts and the message RECYCLE is displayed.
Note: If the vacuum pump
has
run for ten hours or
over

without an oil change the
message
OIL
flashes
on the
display.
Change
the pump oil and
then press
the
SHIFT/

RESET key and
the
zero key to
reset the
oil
change
timer
to zero.
The digital display counts down the evacuation

time.

4.
Check for non-condensibles after five minutes

recycling.
Ifthegauge needles are more than lOpsi
apart purge the non-condensibles from the tank by
open
i ng
the purge valve on the back of the
un
it and
continue to bleed until both needles show the same

reading.

The vacuum sequence continues until the
programmed time has elapsed at which point the
message CPL is displayed.
5. If the moisture indicator turns green recharge with
refrigerant.
or
5. If the moisture indicator has not turned green
replace the unit's filter-drier, which is probably

saturated.

Note:
Pressing
any key at this point allows the next
function to be
accessed.

To recycle the refrigerant only without pulling a
vacuum for an indefinite period of time press the
SHIFT/RESET key and the RECYCLE key on the key­

pad.
Press the SHIFT/RESET key to cancel.
For vacuum only press the SHIFT/RESET key and
the ENTER key and then press
"1".
Run the vacuum
pump as long as required and then press
"1"
or
press SHIFT/RESET to cancel.
8-48 May 1996