OPERATION
The filter-drier performs a filtering action to pre-
vent foreign material in the refrigerant from contam-
inating the expansion valve. A desiccant bag is
mounted inside the filter-drier canister to absorb any
moisture which may have entered and become
trapped within the refrigerant system. In addition,
during periods of high demand air conditioner opera-
tion, the filter-drier acts as a reservoir to store sur-
plus refrigerant.
The filter-drier cannot be repaired. If the filter-
drier is faulty or damaged, or if the refrigerant sys-
tem has been contaminated or left open to the
atmosphere for an indeterminable period, it must be
replaced.
HEATER AND AIR CONDITIONER
DESCRIPTION
All vehicles are equipped with a common heater-
A/C housing assembly (Fig. 4). The system combines
air conditioning, heating, and ventilating capabilities
in a single unit housing mounted under the instru-
ment panel.
OPERATION
Outside fresh air enters the vehicle through the
cowl top opening at the base of the windshield, and
passes through a plenum chamber to the heater-A/C
system blower housing. Air flow velocity can then be
adjusted with the blower motor speed selector switch
on the heater-A/C control panel. The air intake open-
ings must be kept free of snow, ice, leaves, and other
obstructions for the heater-A/C system to receive a
sufficient volume of outside air.
It is also important to keep the air intake openings
clear of debris because leaf particles and other debris
that is small enough to pass through the cowl ple-
num screen can accumulate within the heater-A/C
housing. The closed, warm, damp and dark environ-
ment created within the heater-A/C housing is ideal
for the growth of certain molds, mildews and other
fungi. Any accumulation of decaying plant matter
provides an additional food source for fungal spores,
which enter the housing with the fresh air. Excess
debris, as well as objectionable odors created by
decaying plant matter and growing fungi can be dis-
charged into the passenger compartment during
heater-A/C system operation.
The heater and air conditioner are blend-air type
systems. In a blend-air system, a blend-air door con-
trols the amount of unconditioned air or cooled air
from the evaporator that is allowed to flow through,
or around, the heater core. A temperature control
knob on the heater-A/C control panel determines the
discharge air temperature by moving a cable, which
operates the blend-air door. This allows an almost
immediate manual control of the output air tempera-
ture of the system.
The mode control knob on the heater-A/C control
panel is used to direct the conditioned air to the
selected system outlets. The mode control switch uses
engine vacuum to control the mode doors, which are
operated by vacuum actuator motors.
The outside air intake can be shut off by selecting
the recirculation mode (Max A/C) with the mode con-
trol knob. This will operate a vacuum actuated recir-
culating air door that closes off the outside fresh air
intake and recirculates the air that is already inside
the vehicle.
A large central duct delivers conditioned air from
the front heater-A/C housing to the second and third
seat floor panel foot wells. A damper door in this duct
can be adjusted by the second seat passengers with a
manual control located on a mini-console just behind
the split bench seat center cushion, or located on the
upper rear surface of the floor console on models with
the optional bucket seats. The split bench seat con-
trol has two positions: On or Off. The bucket seat
control has three positions: On, Off and a third posi-
tion that directs air flow through a pair of adjustable
barrel outlets mounted high on the rear surface of
the floor console.
The air conditioner for all models is designed for
the use of non-CFC, R-134a refrigerant. The air con-
ditioning system has an evaporator to cool and dehu-
midify the incoming air prior to blending it with the
Fig. 4 Common Blend-Air Heater-Air Conditioner
System - Typical
1 – TEMPERATURE BLEND/AIR DOOR
2 – EVAPORATOR CORE
3 – BLOWER
4 – PANEL DEFROST DOOR
5 – HEAT DEFROST DOOR
6 – HEATER CORE
7 – RECIRCULATING AIR DOOR
DN HEATING AND AIR CONDITIONING 24 - 7
DESCRIPTION AND OPERATION (Continued)
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