Chevrolet 10 Series 1968, Service Manual

Page: 43 / 713

HEATER AND AIR CONDITIONING 1A-12
TO
CENTER DASH
OUTLET
TO
DEFROSTER
OUTLETS
TO
BALL
DASH
OUTLETS
DEFROSTER
FLOOR DOOR
OUTLET
EVAPORATOR
CORE OUTSIDE
AIR
INLET VALVE
(
TEMPERATURE
DOOR
OUTLETS HEATER
DOOR CORE
BLOWER
ASSEMBLY
RECIRCULATING
AIR INLET
VALVE
F ig . 23—A irflo w Schem atic
“ Outlet” Lever
This lever actuates an air diverter door within the duct
assembly which routes airflow when fully right (HEATER)
to the floor distributor ducts (for heater operation) or
when fully left (A/C) to the dash outlets (for cooling
operation).
Moving this lever toward the left from the HEATER
position will activate the compressor clutch switch and
set the cooling portion of the system in operation pro­
viding the FAN switch is turned on.
When the lever is moved fully toward the right (heating
position) the AIR control lever will automatically move
to the outside air position.
Temperature Lever
The “ TEMPERATURE” lever, through its bowden
cable, actuates the door which controls outlet tempera­
ture. Since the heater core in this system is hot at all
times, this door is necessary to shut off the heat when
not wanted as well as to permit mixing of hot and cool
air to provide the desired conditioned air outlet tempera­
ture, whether during heating or cooling operations.
The temperature door directs the airflow through
either the heater core, the evaporator core or through
both. When the system is set for full cooling, all air
passes through the evaporator core. When warmer out­
let air is desired, the temperature door is moved by the
temperature lever so that some air passes through the
heater core. The warmed air mixes with the cooled air
resulting in a higher outlet air temperature. In the full
HOT position, all air flows through the heater core. For
cooler air, moving the lever toward COOL will send
some air through the evaporator core (inoperative when
the OUTLETS lever is set for heater operation) which in
effect bypasses the heater core resulting in less heat
output.
Air Control Lever
When the control is properly adjusted, full left position
( “ INSIDE” ) will supply 100% recirculated inside air, and
moving the lever to the word “ OUTSIDE” will supply
100% 'outside air to the system. Lever movement con­
trols a vacuum switch which in turn actuates an air inlet
door in the plenum below the air inlet grille and a
recirculating air door in the kick pad.
Defroster
As the A ir control knob is moved to the right from the
“ OUTSIDE” position toward the word DEFROSTER the
diverter door within the distributor duct moves to send a
portion of the airflow to the defroster ducts. Full “ right”
position of the AIR knob, as indicated on the panel, is the
DE-ICE position which sends the total airflow to the
defroster ducts.
Fan Switch
The fan switch controls the operation of the three
speed blower motor.
CHEVROLET TRUCK SERVICE MANUAL