Buick LeSabre 1965 Service Manual page 841

1 1 - 1 0 8 OPTIONAL HEATER-AIR CONDITIONER SYSTEM
ACCESSORIES
5. Evaporator - Dirt or other
foreign matter on the core sur-
face or in the evaporator case
will restrict air flow. A cracked
or broken case can result in
insufficient air or warm air de-
livered to the passenger compart-
ment. The condensation drains
should be unrestricted.
6. Receiver Dehydrator - Leak-
age of refrigerant indicates a de-
fective unit. The desiccant cannot
easily be checked, but if it or the
system has been exposed to out-
side air for a considerable length
of time, the unit s h o u l d be
replaced.
Restrictions in the receiver-de-
hydrator can also cause system
malfunction. If the inlet tube is
blocked, it is likely to result in
high head pressure. If the outlet
tube is blocked, head pressure is
likely to be low and there will be
little or no cooling.
IMPORTANT: The IN stamped on
receiver must be connected to the
condenser.
7. Suction Throttle Valve (STV) -
If the STV is defective it may
cause evaporator pressure to be
too high (air outlet temperature
too warm) or it could cause the
evaporator pressure to be too low
(air outlet temperature too low
which may cause icing of the
evaporator core). Also if the vac-
uum diaphragm of the STV is
defective, there would be no
means of setting the STV to
change the air outlet temperature.
Refrigerant leakage of STV may
be detected through routine leak
detection. Before servicing the
suction throttle, it should be de-
termined that the STV is actually
the cause of the complaint by
following adjustment procedure in
paragraph 11-15, subparagraph
If tests indicate STV is defective,
it should be removed, disassem-
bled and repaired following
procedure in paragraph 11-15,
subparagraph "g" and "h".
c. Use of Receiver Sight
Glass for Diagnosis
At temperatures higher than
70°F., the sight glass may indi-
cate whether t h e refrigerant
charge is sufficient. A shortage
of liquid refrigerant is indicated
after about five minutes of com-
pressor operation by appearance
of slow-moving bubbles (vapor)
or a broken column of refrigerant
under the glass. Continuous bub-
bles may appear in a properly
charged system on a cool day.
This is a normal situation. If the
sight glass is generally clear and
performance is satisfactory, oc-
casional bubbles do not indicate
refrigerant shortage.
If the sight glass consistently
shows foaming or a broken liquid
column, it should be observed
after partially blocking the air to
the condenser. If under this con-
dition the sight glass clears and
the performance is otherwise sat-
isfactory, the charge shall be
considered adequate.
In all instances where the indi-
cations of refrigerant shortage
continues, additional refrigerant
should be added in 1/4 lb. in-
crements until the sight glass is
clear. An additional charge of
1/2 lb. should be added as a
reserve.
In no case should the system be
overcharged.
COMPLAINT AND CAUSE
1. Insufficient Cooling
(a)
(b)
(c)
NOTE
test on
Low air flow
Defective heater core manual water
valve
Heater, defroster, or ventilator controls
not in the off position
If none of the above items are cause of
i car. If car does not pass test see items 2,
CORRECTION
(a) Check blower operation. Check for ob-
structions in air distribution system. Check
for clogged evaporator. If iced, deice core
and check adjustment and operation of suc-
tion throttle valve. Paragraph 11-15, sub-
paragraph "f".
(b) Check operation of valve. Adjust or replace
as necessary.
(c) Advise operator of correct operation of
controls.
complaint of insufficient cooling, perform functional
3, 4 and 5 on this chart.