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AIR-CONDITIONING-Service
Adiustment
Procedures
24-35
CORRECTING
LOW REFRIGERANT
LEVEL
Suction
Discharge
gauge
gauge
I
\-
a/
gauge
valve
II II
Discharge
gauge
Ho\t water
52°C i 125°F)
2OUO325
Since the refrigeration
system
is completely
sealed, refrigerant
level will not be low unless there is a leak in the
system.
Before
adding
refrigerant
when the cause of low level is not known,
the system
should be tested
for leaks.
Assuming
that leaks have been corrected
without
discharging
the system,
proceed with partial charge.
Install and connect
manifold
gauge set.
(I) Close both gauge set manifold
valves.
(2) Connect the suction gauge test hose to the suction port of the compressor.
Connect the discharge
gauge test
hose to the discharge
port.
(3) Connect one end of long test hose to center manifold
outlet, other end to refrigerant
dispensing
manifold.
(4) Close two dispensing
manifold
valves and open remaining
dispensing
manifold
valve. Remove
protective
cap
from opened valve.
(5) Screw a can of R-12 to the opened manifold
valve. Be sure gasket is in place and in good condition.
Tighten
refrigerant
can and manifold
locking nut to insure a good seal. Do not overtighten.
8 to 11 Nm (6 to 8 ft.lbs.) is
sufficient
if gasket is in good condition.
(6) Turn manifold
valve (above the refrigerant
can) completely
clockwise
to puncture
the can. This closes the valve
and seals the refrigerant
in the can.
Caution
Never heat small cans of refrigerant
over 52°C (125'F) as they may explode.
(7) Place the refrigerant
in a large pan of water heated to 52°C (125°F). Place pan of water containing
the refrigerant
can on an accurate
scale so the amount
of refrigerant
added can be weighed.
Open the refrigerant
manifold
valve.
(8) Purge all air from test hoses.
Air in the system will be trapped
in the condenser
causing abnormally
high
discharge
pressures
and interfering
with condensing
of the refrigerant.
(9) Slightly loosen both test hoses at the gauge set manifold.
Tighten
the hoses as soon as the air is purged.
(10)Slightly
loosen charging
hose connection
at gauge set manifold.
This will purge air from the charging
hose.
Tighten
connection
as soon as air is purged.
(1l)With
vehicle windows
open and hood up, operate engine at 1,500 rpm and jump the switch terminals
located
on so the clutch will remain engaged.
(12)Place air conditioner
control
on air conditioner
and place the blower switch on high.
(13)lf necessary,
block the condenser
to maintain
a discharge
pressure
of 1,422 to 1,520 kPa (206 to 220 psi.).
System
must be charged through
the evaporator
suction
service ports as follows:
(a) Slowly open the
suction
service gauge valve.
Meter flow of refrigerant
by adjusting
the suction
service
gauge valve so that pressure
registered
at the suction
service gauge does not exceed 345 kPa (50 psi).
Keep refrigerant
container
upright.
(b) Add refrigerant
gas until there is no foam visible at the sight glass.
(c) Close the suction
gauge valve.
Caution
Too much refrigerant
in the system can cause abnormally
high discharge
pressures. Care must be
used so that the exact recommended
amount
of refrigerant
is added after foam clears in the sight
glass.
(d) Close dispensing
manifold
valve. Remove
test hoses and adapters
from the service ports of compressor,
install protective
caps at service ports and reconnect
wiring.
/ STB Revision
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