Chevrolet 1980 Light Duty Truck Service Manual page 29

Standard Heater.
Auxiliary Heater
Specifications.....
General Description.......................................................1A-1
System Components.....................................................1A-1
System Controls.......................................................... .1A-3
Diagnosis.........................................................................1A-4
On Vehicle Service
Blower Motor.............................................................. .1A-8
Heater Distributer and Core Assembly................... .1A-8
Heating components are attached to the dash panel on
the right side of the vehicle. The blower and air inlet
assembly and water hoses are located on the forward side
of the dash panel while the heater core and distributor duct
are on the passenger side.
The heater system is an air mix type system in which
outside air is heated and then mixed in varying amounts
with cooler outside air to attain the desired air temperature.
The system consists basically of three parts: (1) the blower
and air inlet assembly, (2) the heater distributor assembly
and (3) the heater control assembly.
HEATER AIR FLOW S C H E M A TIC
CK Series heater airflow is shown in Figure 1A-1.
BLOWER AND AIR INLET ASSEM BLY
The blower and air inlet assembly draws outside air
through the outside air inlet grille located forward of the
windshield reveal molding and channels the air into the
heater distributor assembly. The operation of the blower
motor is controlled by the FAN switch on the heater
control. The motor is connected in series with the FAN
switch and also the blower resistor assembly. Located in the
fuse block, in series between the blower motor and the
battery, is a 25 amp. fuse C-K models - a 20 amp fuse on
G models.
SECTION 1A
HEATER
CONTENTS OF THIS SECTION
STANDARD HEATER
INDEX
GENERAL DESCRIPTION
HEATER DISTRIBUTOR ASSEM BLY
and the doors necessary to control mixing and channeling
of the air. Since the unit has no water valve, water
circulation keeps the core hot at all times. That portion of
the air passing through the core receives maximum heat
from the core. Air entering the distributor assembly is
channeled as follows:
C-K Models
purge door opening, on the right end of the distributor
assembly, by the purge door. If the purge door is closed,
then air is directed through and/or around the heater core
by the temperature door. Air is then directed into the
passenger compartment through the heater (floor) outlets
and/or the defroster (dash) outlets by the defroster door.
The temperature of the outlet air is dependent on the ratio
of heated to unheated air (controlled by the temperature
door).
G Models
assembly. The air door can be adjusted to vary airflow. If
air is allowed to enter the distributor assembly, it is then
directed through and/or around the heater core by the
temperature door. Air is directed into the passenger
compartment through the heater (floor) and/or defroster
(dash) outlets by the defroster door. The temperature of the
1A-1
1A-15
1A-19
Heater Hoses............................................................... ..1A-9
Center Distributor Duct - G Models....................... ..1A-9
Defroster D uct............................................................ ..1 A -12
Control Assembly....................................................... ..1A-12
Control Cables............................................................ ..1A-13
Blower Switch............................................................. ..1A-13
Resistor U nit............................................................... ..1A-13
The heater distributor assembly houses the heater core
Air entering the distributor can be directed out the
Air flow is controlled by doors in the distributor
HEATER 1 A-1
LIG H T T R U C K S E R V IC E MANUAL