Chrysler DODGE D150 1993 Service Manual page 1456

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HEATING AND AIR CONDITIONING 24 - 19
Connect t h e compound gauge hose to t h e compres­
sor suction service valve gauge port (low-side).
Connect t h e high pressure gauge hose to the dis­
charge service valve gauge port (high-side).
Purge air from the high side test hose by opening
the high side hand valve on t h e manifold for 3 to 5
seconds. The center connection on t h e manifold must
be open.
Purge air from t h e low side test hose by opening
the low side hand valve on the manifold for 3 to 5
seconds. The center connection on t h e manifold must
be open.
The air conditioning system may be operated with
the gauge manifold assembly connected in this man­
ner. The gauges will indicate respective operative
pressures.
DISCHARGING THE SYSTEM
Since the air conditioning refrigerant system is
pressurized, it will be necessary to completely dis­
charge the system before replacing any refrigerant
components. The procedure is as follows:
(1) Install gauge set as described under manifold
gauge set installation. Make sure t h e gauge set
valves are closed before attaching the hoses to the re­
frigerant system.
(2) Install a long hose to the manifold gauge set
connector. Run this hose to the oil collector can near
the shop exhaust system.
A good oil collector can may be made from a large
empty coffee can with a plastic top. Slit the plastic
top in the form of a Y to make an entrance for the
refrigerant hose and exit for the gas.
(3) Open t h e compressor discharge and suction line
pressure valves and discharge the refrigerant into
the oil collector can. Watch to make sure the hose
does not blow out of the collector can.
(4) When t h e system has been completely dis­
charged, measure t h e amount of oil collected in t h e
can. The amount of oil measured should be added to
the refrigerant system before it is charged. Discard
the used oil. Add new oil.
EVACUATING THE SYSTEM
Whenever t h e system has been opened to the atmo­
sphere, it is absolutely essential t h a t the system be
evacuated to remove all the air and moisture. Air in
the refrigerant system causes high compressor dis­
charge pressures, a loss in system performance, and
oxidation of t h e compressor oil into gum and varnish.
Moisture in t h e refrigerant system can cause the ex­
pansion valve to malfunction. Under certain condi­
tions it can react with the refrigerant to form
destructive acids. It is necessary to adhere to the fol­
lowing procedure to keep air and moisture out of t h e
system.
(1) Connect the manifold gauge set to t h e compres­
sor and long test hose from manifold gauge set center
connection to Vacuum Pump Tool C-4289.
(2) Open both manifold gauge set valves.
(3) Start t h e vacuum pump and operate until t h e
evaporator suction gauge registers a t least -88 kPag
(26 inches of vacuum). If at least -88 kPag (26 inches
of vacuum) cannot be obtained, either the system h a s
a leak or the vacuum pump is defective. Check t h e
vacuum pump. If the pump proves to be functioning
properly, the system h a s a leak. Charge t h e system
with 1 pound of refrigerant. Locate and repair all
leaks. Discharge the refrigerant and evacuate t h e
system.
(4) Continue to operate t h e pump for a t least 5
minutes.
(5) Close manifold valves. Turn off t h e vacuum
pump and observe evaporator suction gauge for 2
minutes. The vacuum level should remain constant.
If the vacuum level falls off, the system h a s a leak.
Charge the system with 450 g (1 pound) of refriger­
ant. Locate and repair all leaks. Discharge the sys­
tem and repeat evacuation procedure.
CHARGING THE SYSTEM
The refrigerant system must have been evacuated
using t h e previous procedure before charging. Charge
using only R-12 refrigerant. R-12 is available in bulk
tanks or 437 g (14 oz.) cans.
The special refrigerant dispensing manifold per­
mits charging 3 cans of refrigerant a t a time. When
using disposable cans of this type, carefully follow
the can manufacturers instructions.
W A R N I N G : N E V E R U S E T H E S E C A N S T O C H A R G E
I N T O T H E H I G H P R E S S U R E S I D E O F T H E S Y S T E M
( C O M P R E S S O R D I S C H A R G E P O R T ) O R I N T O A
S Y S T E M T H A T I S A T H I G H T E M P E R A T U R E . T H E
H I G H S Y S T E M P R E S S U R E S C O U L D B E T R A N S ­
F E R R E D I N T O T H E C H A R G I N G C A N C A U S I N G IT
T O E X P L O D E .
Keep t h e refrigerant manifold valves capped when
not in use. Keep a supply of extra refrigerant-can-to
refrigerant-manifold gaskets on hand so the gaskets
can be replaced periodically. This will insure a good
seal without excessive tightening of the can or t h e
manifold nuts.
(1) Attach center hose from manifold gauge set to
refrigerant dispensing manifold. Turn refrigerant
manifold valves completely counterclockwise so they
are fully open. Remove protective caps from refriger­
ant manifold.
(2) Screw refrigerant cans into manifold. Be sure
manifold-to-can gasket is in place and in good condi­
tion. Tighten can and manifold nuts to 9.5 N»m (7 ft.
lbs.) torque.