C2J
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Ro/ls-Royce
&
Bent
l
ey
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Air
Conditioning
System
Manual
PRESSURE
TESTS
Before taking readings, the
car
should
be sighted
in
a well-ventilated position
to
ensure
an
adequate flow
of
air
over
the
condenser.
It
is advisable
to
place a
fan in front
of
the
radiator
for
additional
air
flow
over
the condenser
if
the
system is
to
be operated
over
a long period.
Check
the
security
of
the
radiator
cap,
after topping-up
the
coolant
level
as
necessary.
The
'blow-off' pressure is 7 lb/sq. in.
and
the
pressure
relief valve is located
under
the detachable plate on
top
of
the
radiator
header tank,
or
is incorporated in
the filler cap.
Switch
OFF
and
insta!l
the
manifold gauge set
on
the
compressor valve service
ports
with
both
its
valves firmly closed. Remove
the
protection caps
from the compressor service valves
and
just
crack
open
both
valves by rotating
one
half
turn m a
clockwise direction.
During
these tests, it is essential
that
the
com-
pressor service valves are
not
fully opened, as this
closes the system delivery and
damage
to
the com-
pressor
and
lines could occur.
Run
the
engine
at
a fast idle with the Air
Con-
ditioning
system operating
as
previously mentioned.
Turn
the
compressor
service valves
ANTI-CLOCK-
WISE as necessary
to
damp
out
gauge fluctuation.
The
compound
gauge reading should be 15-30
lb/sq. in.
With
the
following ambient
air
temperatures
(temperature recorded
in
the shade),
the
pressure
gauge reading should be
as
follows:
60°F (15·6°C) 100---150 lb/sq. rn.
80°F (26·7°C) 140---190 lb/sq. m.
l00°F
(37·8°C) 180---240 lb/sq.
Ill,
110°F (43·3cq
2(5-270
lb/sq. in.
N.8.-The
maximum reading for each
of
the
above temperatures would only apply
if
very little
air
flow is allowed
to
pass
over
the condenser.
DIAGNOSIS
Set the
compressor
valves t a
turn
clockw
is
e from
the
fully antt-clockwi.se position.
A low reading
on
the high pressure gauge
coupled
with a high reading
on
the
compound
gauge, indicates
a defective compressor head gasket
or
valve plate
gasket
or
:1
defective valve. (See
Section-Valve
Plate and Gaskets).
Fig. 18 Manifold Gauge
Set
in position
Section C6
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