Buick LeSabre 1965 Service Manual page 838

ACCESSORIES
OPTIONAL HEATER-AIR CONDITIONER SYSTEM 1 1 - 1 0 5
1 1 - 1 9 AIR CONDITIONER
FUNCTIONAL TEST
In order to determine if the air
system is operating properly and
efficiently, it should be functional
tested. Functional testing the air
conditioner is determining if the
discharge air temperature at the
air outlet located at right side of
the instrument panel, suction
pressure and discharge pressure
are within the specifications at
a particular ambient condition.
See Figures 11-154 and 11-155.
1 1 - 2 0 AIR CONDITIONER
TROUBLE
DIAGNOSIS
NOTE: If a case is encountered
on a 49000 Series where the air
conditioner has a refrigerant leak
and there has been difficulty de-
tecting it, there is a possibility
that the piston diaphragm in the
suction throttling valve may be
the cause of the leak. If the
piston diaphragm is leaking, the
refrigerant will be drawn into the
engine intake manifold through the
vacuum hose and there will be no
indication that the suction throttle
valve has an external leak. Thus,
when checking the air conditioner
system for leaks, remove the
vacuum hose from the suction
throttle valve vacuum diaphragm,
wait several seconds to allow re-
frigerant to collect in the dia-
phragm and leak t e s t at the
vacuum hose connection on the
diaphragm. If leak detector in-
dicates a leak, it will be nec-
essary to remove suction throttle
valve and replace the piston dia-
phragm in the valve.
a. Inspection of Air
Conditioner System
1. Check compressor belt ten-
sion. See Figures 2-47 and 2-48.
2. Inspect all connections for
presence of oil on any of the re-
frigerant system parts which
could indicate a refrigerant leak.
If oil is evident, check for leaks
and repair as necessary.
3. Check air outlet hoses for
leaks or restrictions.
4. Check outer surface of con-
denser to be sure they are not
plugged with dirt, leaves or other
foreign material. Be sure to
check between the condenser and
radiator as well as the outer
surfaces.
5. Check to insure the evapora-
tor drains are open.
6. Check sight glass as instructed
in subparagraph "c".
7. Check ambient air temperature
and air temperature at right air
outlet following instructions on
functional test charts. See Fig-
ures 11-154 and 11-155. Tem-
perature should correspond with
those listed on chart. If temper-
atures do not compare, attach
gauge set (Figure 11-153) and
functional test air conditioner.
b. Diagnosis of Components
Listed below are the air condi-
tioner components and the pos-
sible conditions that could be
encountered with each unit if
defective.
1. Compressor - Compressor
malfunction will appear in one of
four ways: noise, seizure, leak-
age, or low discharge pressures.
Even resonant compressor noises
are not cause for alarm; however,
irregular noises or rattles are
likely to indicate broken parts.
Seizure will be indicated by the
failure of the compressor to op-
erate, if the clutch is in good
operating condition, and there is
no break in the electrical contin-
uity of the system. Continued op-
eration of a seized or partially
seized compressor will result in
damage to the clutch. To check
for seizure, de-energize the
clutch and attempt to rotate the
compressor shaft. If the shaft
will not turn, the compressor is
seized. Leakage of compressor
refrigerant may be detected
through routine leak detection.
Low discharge pressures may
also be caused by insufficient re-
frigerant or a restriction else-
where in the s y s t e m . These
should be checked out prior to
compressor servicing.
2. Compressor Clutch - If the
compressor is inoperative, the
electrical wires to the clutch
should first be checked. If there
is current to the clutch and the
compressor is not seized, the
clutch is defective and should be
repaired.
3. Condenser - There are two
types of possible condenser mal-
functions. The condenser may
leak, resulting in loss of refrig-
eration and low system pres-
sures, or the condenser may have
a restriction, resulting in exces-
sive compressor discharge pres-
sures, and inadequate cooling. If
a restriction occures and some
refrigerant passes the restric-
tion, icing or frost may occur on
the external surface of the con-
denser in the area of the re-
striction. Also if the air flow
through the condenser i s re-
stricted or blocked, high dis-
charge pressures will result. It
is important that the external fins
of the condenser and radiator
core are not plugged with bugs,
dirt, etc.
4. Expansion Valve - If malfunc-
tion of the valve is suspected,
make sure the power element bulb
is in proper position, tightly at-
tached, and well insulated from
outside air temperatures. If this
valve fails, it usually fails in the
power element and thus the valve
remains closed. This will be in-
dicated by low suction and dis-
charged pressures. Also the inlet
screen could be plugged. The
screen may be cleaned with liquid
refrigerant.