Buick LeSabre 1965 Service Manual page 801

1 1 - 6 8 OPTIONAL HEATER-AIR CONDITIONER SYSTEM
ACCESSORIES
Air Conditioning Checkout Sequence and Trouble
Diagnosis—45000, 46000 and 48000 Series (Cont.'d)
Sequence of
Operation of
Controls
Move WARMER lever fully to
right.
Move DEFROST lever fully to
the right.
Changes That Should Take
Place in the System
Vacuum will be applied to dia-
phragm of w a t e r valve and
open valve permitting coolant
to circulate thru heater core.
Warm air will flow from
heater outlets.
The t e m p e r a t u r e door will
open permitting air to circu-
late past the heater core.
Air will be directed to de-
froster outlets.
Possible Cause of
Malfunctions
Kinked vacuum hoses.
Defective water valve and STV
vacuum disc switch.
Vacuum h o s e s reversed at
vacuum diaphragm or con-
nector plug on cowl.
Kinked water hoses.
Defective water valve.
Plugged heater core.
Broken, defective or misad-
justed control cable.
Broken, d e f e c t i v e , discon-
nected or misadjusted control
cable.
1 1 - 1 4 AIR DISTRIBUTION
SYSTEM OPERATION
AND TROUBLE
DIAGNOSIS—
4 9 0 0 0 SERIES
a. System Operation
The vacuum circuit for the 49000
Series heater-air conditioner is
as shown on Figure 11-80. The
Htr.-A/C diaphragm regulates the
opening and closing of the heater
and air conditioner air door. The
outside and recirculated dia-
phragm opens and closes the out-
side and recirculated air door.
When vacuum i s not present
on the dual stage vacuum dia-
phragm for the outside and re-
circulated air door, the door is
held in the closed position by a
spring. Similarly, the heater and
evaporator door is held closed
and the air flow is directed thru
the heater assembly. If vacuum
is applied to only one stage of the
vacuum diaphragm of the outside
and recirculated air door, the
door will partially open to the re-
circulated position. If vacuum is
applied to only one stage of the
vacuum diaphragm of the heater
and evaporator air door, the door
will partially open to the heat and
A/C position (see Figure 11-86)
to permit air flow to both the
evaporator and heater assem-
blies. Application of vacuum to
both stages of the vacuum dia-
phragm for the heater and evapo-
rator air door will draw the door
fully open, and duct all air flow
to the air conditioner outlets.
When vacuum is applied to both
stages of the outside and recir-
culated air door vacuum dia-
phragm, the door will be drawn
fully open and block off all re-
circulated air flow. The inter-
r e l a t i o n s h i p b e t w e e n the
DEFROSTER, HEATER TEMP
and air conditioner temperature
control levers, and their affect
on the vacuum diaphragms is
shown in Figures 11-80 and
11-81. The various positions of
the air doors for each mode of
operation is shown in Figures
11-82 thru 11-86.
b. Trouble Diagnosis—
49000 Series
If the heater-air conditioner sys-
tem is not functioning properly,
first check the vacuum hose con-
nections and the control cable
adjustments. If this does not cor-
rect complaint, check for vacuum
at diaphragms, for proper func-
tioning of vacuum disc switches
and position of air doors as shown
in Figures 11-82 thru 11-86. Re-
fer to trouble diagnosis chart for
possible causes of complaint.
IMPORTANT: If complaint is
that air flow changes or shuts off
when car is accelerated, check
valve at intake manifold may be
defective. Also, if there is no
vacuum to suction throttle valve
(air conditioner temperature con-
trol lever is on low), check for
the vacuum hoses being off vacu-
um modulator, hoses being kinked
or modulator being defective.