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AIR CONDITIONING
24-7
fresh air conditioning.
fresh air conditioning.
(2)
Medium speed-fresh air heating, defrosting, or
(3) Medium speed-recirculating air conditioning.
(4)
High speed-recirculating air conditionng.
NOTE:
The heater and defroster are not intended
to be operated with the "Blower" switch in either
the
No.
3
or
No. 4
positions; therefore, the blower
will not operate for these settings.
Directional air conditioning outlets on the instru-
ment panel also serve for defrosting. Two spot cool-
ers also are provided; one at the left lower edge of
the instrument panel, the other at the right kick panel
area (Fig. 3). Additional outlets under the instrument
panel direct cooling air down to floor level.
Air Flow for Each Push Button Position
When testing or adjusting the doors in the distribu-
tion system, it is necessary to know the correct posi-
tion of each door for each push-button position. It is
also necessary to know which vacuum hoses are ac-
tivated for each push-button position. In the illustra-
tions (Figs.
4
thru 9) which follow; air flow is indi-
cated, also which vacuum actuator hoses are activated
for each push-button position.
Ventilation
Pushing either the "Heat" or "Defrost," buttons
with the blower switch on positions 1 or
2
and mov-
ing the temperature control lever to the off position,
will set the system for fresh-air ventilation-a
desir-
able setting when temperature conditions are such
that neither cooling nor heating is desired. The only
difference between the operation of the heat system
with the "Heat" or "Defrost" buttons pushed in is the
circulation of the discharge air. With the "Heat" but-
ton in, most of the air is discharged through the floor
level. With the "Defrost" button in, most of the air is
discharged through the instrument panel outlets.
ELECTRICAL CONTROLS AND CIRCUITS
With air conditioning there are two switches. The
push button switch assembly controls the clutch cir-
cuit. The push button switch also controls the "Feed"
\
Fig. 1 I-Thermostatic
Valves
circuit to the blower motor speed control rotary
switch mounted on the instrument panel.
Push Button Control
The power "feed" circuit is shown in Figure 10. A
20 ampere fuse in the fuse block accessory terminal,
controls the blower speeds and the clutch feed.
The clutch circuit is energized ("hot") only when
the "Cool" push button is depressed. The power
"feed" circuit to the blower motor speed control
switch is energized ("hot") when any button other
than the "Off" button is depressed.
Blower Motor Speed Control Switch
The power "feed" line from the push-button switch
to the blower speed control switch is energized only
when the ignition is on and any push button other
than "Off" is depressed.
The blower speed control rotary switch has no off
position.
Position NO. 1 Low Speed and NO. 2 Medium Speed
are in the "heat" and "cool" range. Position NO. 3
Medium and NO.
4
High Speed are in the "cool"
range (Fig. 2). The design of the blower control elec-
trical circuit prevents the blower switch operation in
positions NO. 3 and NO.
4
except when the "cool"
push button is depressed.
Attached to the blower motor speed control switch
is a maximum cool vacuum switch. This switch closes
the fresh air door when the rotary movement of the
speed control switch is turned to the NO. 3 or
4
posi-
tion.
THERMOSTATIC VALVES
Mounted on the face of the evaporator housing are
two thermostatic valves (Fig. 11). These valves sense
the temperature of the air leaving the heater core and
modulate the valve which controls the water flow
valve. The left-hand thermostatic valve or heat stat is
for heating and defrosting operation. It is identified
by two yellow dots on the end of the valve. The right-
hand thermostatic valve or air conditioning stat gov-
erns reheating when the air conditioning is operating.
This valve has two green dots on the end.
The temperature control lever at the instrument
panel is connected to both valves by a short control
cable. Because the two stat valve levers are linked to-
gether, they both move when the temperature control
lever is moved. Inside the evaporator housing, the
lever operates a cam which varies the tension on a
U-shaped bimetal thermostat spring. This spring
opens and closes the vacuum valve in response to
changes in the temperature of the air being dis-
charged from the unit. Except for the contours of the
cams, both thermostatic valves are identical. The cam
shape determines the effective operating range of each
valve.
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