System Checking With The Manifold Gauge Set; Connecting The Manifold Gauge Set; Stabilising The System - Aston Martin DB7 Workshop Manual

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Air Conditioning
System Checking with the Manifold Gauge Set
System Checking with the Manifold
Gauge Set
Connecting the Manifold Gauge Set
Caution: Only use hoses with connectors which are
dedicated to HFC 134A charge ports.
Attachmentofthehosequick release connectors to
the high and low side system ports is straightforward,
provided that the high and low valves are closed
and the system is NOT operational.
Assessment ofthe system's operating system can be
carried out by using the facilities ofthe Recovery-
R e c h a r g i n g - R e c y c l i n g s t a t i o n . F o l l o w the
manufacturer's instructions carefully and closely
observe the safety procedures.
Warning: Under no circumstances should the connections
be made with the system in operation or the valves
open. Should the valves be open and a vacuum
pump or refrigerant container attached, an
explosion could occur as a result of high pressure
refrigerant being forced back into the vacuum
pump or container.
Stabilising the System
Accurate test gauge data can be attained only if the
system temperatures and pressures are stabilised.
Ensure that equipment and its hoses cannot come
into contact with moving parts or heat sources.
It is recommended that a free standing air mover is
placed in front of the vehicle to provide mass air
flow through the condenser-cooling system.
Checking Procedure
Connecting the Gauge Set.
A test hose connected to the fitting directly under
the low side gauge is used to connect the low side
ofthe test manifold into the low side ofthe system,
and a similar connection is found on the high side.
When connecting the gauge manifold set to the air
cond ition i ng system an access va Ive core removi ng
tool is available for connecting the test hoses to the
high and low sides ofthe system.
Using the valve removing tool it enables the valve
core to be removed and held back inside the tool
eliminating restrictions and, thereby, providing a
full flow of refrigerant.
Warning: Do not open the high side hand valve while the
air conditioning system is in operation because,
high pressure refrigerant will be forced through
the high side gauge and to the refrigerant container,
if it is attached. This could cause the container to
rupture or the fitting at the safety container valve
to burst resulting in damage and personal injury.
1. With theengineswitched off, remove the protective
caps from the schraeder valves.
2. Fit the access valve removal tool to the schraeder
valves. Ensure that both the manifold hand valves
are in the closed position.
3. Connect the high pressure manifold gauge hose (to
the high pressure side of the air conditioning side of
the system (high side is always the line from the
compressor to the condenser). Connect the low
pressure or compound gauge hose to the low
pressure side ofthe air conditioning system.
4. Using the access valve removal tool loosen and
screw out the valve cores.
1. Start the engine and allow it to attain normal
working temperature then set it at fast idle (typically
1200 to ISOOrpm).
2. Select full air conditioning performance.
3. With all temperatures and pressures stable or
displaying symptoms of faults, begin relevant test
procedures.
May 1996 8-39