General Description; C60 System (C -K & G M Odels; Motor Home Chassis System - Chevrolet 1981 Light Duty Truck Service Manual

C60 A /C SYSTEM
Both the heating and cooling functions are performed
by this system. Air entering the vehicle must pass through
the cooling unit (evaporator) and through (or around) the
heating unit, in th at order, and the system is referred to as a
"re h e a t" system.
The evaporator provides m axim um cooling of the air
passing through the core when the air conditioning system is
calling for cooling.
On C-K and G Series, compressor operation is control­
led by a pressure sensing switch, located near the top of the
accum ulator. The switch responds to pressure changes to
turn the compressor O N or O FF, as required.
System operation is as follows:
Air, either outside air or recirculated air, enters the
system and is forced through the system by the blower. As
the air passes th ro u g h th e evap orator core, it receives
m axim um cooling if the air conditioning controls are calling
for cooling. A fter leaving the evaporator, the air enters the
heater and air conditioner selector duct assembly where, by
m eans of diverter doors, it is caused to pass through or to
bypass the heater core in the proportions necessary to
provide the desired outlet tem perature. Then conditioned air
enters the vehicle through either the floor distributor duct or
the dash outlets. D uring cooling operations, the air is cooled
by the evaporator to below com fort level, it is then warmed
by the heater to the desired tem perature. During "heating
only" operations, the evaporator will not be in operation and
am bient air will be warm ed to the desired level in the same
m anner.
AIR DISTRIBUTION OUTLETS
C-K Series
The dash outlets are rectangular in design. The outlets
can be rotated horizontally or vertically to direct air as
desired. U nder the left distributor duct is located a floor
cooler which can be rotated to provide cooling air or shut off
completely.
G-Van
The dash outlets are rectangular in design and can be
rotated horizontally or vertically to direct air as desired.
Foot coolers are provided on both driver and passenger side.
In th e h eater-d efro st m odes, th e air conditioning
outside air door is closed. The heater air door is open and
outside air is allowed to pass th ro u g h the h eater core
(receiving m axim um heating) and is then directed into the
passenger com partm ent through the heater an d/or defroster
outlets.
OVERHEAD SYSTEMS (C-K & G SERIES)
These systems (C69 on C-K & G Series) operate in
conjunction w ith the C 60 S y s te m -th e y do not operate
independently. However, control of rear blower motor speed
is possible even when the front system is O FF, thus, rear air
circulation without the refrigerant function may be had by
operating the rear blower control switch.
These units are self contained, operating on inside
(recirculated) air only. A ir is draw n into the unit, passed
through the evaporator core and then directed into the
passenger com partm ent through the air distributor duct.

GENERAL DESCRIPTION

control on the overhead system is a three speed blower
switch.

MOTOR HOME CHASSIS SYSTEM

heating (above am bient tem peratures) is desired, the vehicle
heater must be used. W hen air conditioning is desired, the
heater should be completely shut O FF.
by the body m anufacturer. It operates on inside (recircu­
lated) air only. A ir is drawn into the unit, passed through
the evaporator core (receiving maxim um cooling) and then
directed into the vehicle through adjustable outlets.
to control compressor operation by sensing air tem perature
as it leaves the evaporator core.
System Components
Receiver-Dehydrator (Motor Home Chassis
Models)
storage of high pressure liquid produced in the condenser,
incorporates a screen sack filled with the dehydrating agent.
storage tank, also functions to trap minute quantities of
m oisture and foreign m aterial which may have rem ained in
the system a fte r installation or service operations. A
refrigerant sight glass is built into the receiver-dehydrator to
be used as a quick check of the state and condition of charge
of the entire system. The receiver-dehydrator is mounted
near the condenser.
Sight Glass (Motor Home Chassis Models Only)
the sight glass is a valuable aid in determ ining w hether or
not the refrigerant charge is sufficient and for elim inating
some guess work in diagnosing difficulties. The sight glass, is
built into the receiver-dehydrator outlet connection and is
designed and located so th a t a shortage of refrigerant at this
point will be indicated by the appearance of bubbles beneath
the glass. The dust cap provided should be kept in place
when the sight glass is not in use.
Thermostatic Expansion Valve (Fig. IB-2)
use a therm ostatic expansion valve in place of a float system.
body, actuating pins, seat and orifice. A t the high pressure
liquid inlet, is a fine mesh screen which prevents dirt, filings
or other foreign m atter from entering the valve orifice.
pressure liquid refrigerant enters the valve through the
screen from the receiver-dehydrator or condenser and passes
on to the seat and orifice. Upon passing through the orifice
the high pressure liquid becomes low pressure liquid. The
low pressure liquid leaves th e valve and flows into the
evaporator core where it absorbs heat from the evaporator
core and changes to a low pressure vapor, and leaves the
evaporator core as such. The power element bulb is clamped
System control is through the front system. The only
This system performs the cooling functions only. W hen
This self-contained unit is bracket m ounted to the dash
A therm ostatic switch, located on the face plate is used
T he receiver-dehy drator, serving as a reservoir for
The receiver-dehydrator, used prim arily as a liquid
W hile having no real function to perform in the system,
C-K and G overhead, and motor home chassis systems
The valve consists prim arily of the power element,
W hen the valve is connected in the system , high
AIR CONDITIONING IB-3
LIG H T T R U C K SERVICE M A N U A L