Workshop Manual

1A–20
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
A condenser may malfunction in two ways: it may leak, or
it may be restricted. A condenser restriction will result in
excessive compressor discharge pressure. If a partial
restriction is present, the refrigerant expands after
passing through the restriction.
Thus, ice or frost may form immediately after the
restriction. If air flow through the condenser or radiator is
blocked, high discharge pressures will result. During
normal condenser operation, the refrigerant outlet line will
be slightly cooler than the inlet line.
The vehicle is equipped with the parallel flow type
condenser. A larger thermal transmission area on the
inner surface of the tube allows the radiant heat to
increase and the ventilation resistance to decrease.
The refrigerant line connection has a bolt at the block
joint, for easy servicing.
875R200015
Legend
(1) Pressure Switch
(2) Receiver Drier
(3) Condenser & Receiver Tank Assembly
(4) Condenser Fan
Receiver / Drier
The receiver/drier performs four functions:
B As the quantity of refrigerant circulated varies
depending on the refrigeration cycle conditions,
sufficient refrigerant is stored for the refrigeration
cycle to operate smoothly in accordance with
fluctuations in the quantity circulated.
B The liquefied refrigerant from the condenser is mixed
with refrigerant gas containing air bubbles. If
refrigerant containing air bubbles. If refrigerant
containing air bubbles is sent to the expansion valve,
the cooling capacity will decrease considerably.
Therefore, the liquid and air bubbles are separated
and only the liquid is sent to the expansion valve.
B The receiver/drier utilizes a filter and drier to remove
the dirt and water mixed in the cycling refrigerant.
A receiver/drier may fail due to a restriction inside the
body of the unit. A restriction at the inlet to the
receiver/drier will cause high pressure.
Outlet restrictions will be indicated by low pressure and
little or no cooling. An excessively cold receiver/drier
outlet may indicate a restriction.
The receiver/drier of this vehicle is made of aluminum
with a smaller tank. It has a 300cc refrigerant capacity.
The refrigerant line connection has a bolt at the block
joint, for easy servicing.
Triple Pressure Switch (V6, A/T)
Triple pressure switch is installed on the upper part of the
receiver/drier. This switch is constructed with a unitized
type of two switches. One of them is a low and high
pressure switch (Dual pressure switch) to switch “ON” or
“OFF” the magnetic clutch as a result of irregularly
high–pressure or low pressure of the refrigerant. The
other one is a medium pressure switch (Cycling switch) to
switch “ON” or “OFF” the condenser fan sensing the
condenser high side pressure.
Compressor
ON
(kPa/psi)
OFF
(kPa/psi)
Low-pressure
control
206.0±30.0
(29.8±4.3)
176.5±24.5
(25.6±3.6)
High-pressure
control
2353.6±196.1
(341.3±28.4)
2942.0±196.1
(426.6±28.4)
Condenser fan
ON
(kPa/psi)
OFF
(kPa/psi)
Medium-pressure
control
1471.0±98.1
(213.3±14.2)
1078.7±117.7
(156.4±17.1)
Expansion Valve
This expansion valve is an external pressure type and it is
installed at the evaporator intake port.
The expansion valve converts the high pressure liquid
refrigerant sent from the receiver/drier to a low pressure
liquid refrigerant by forcing it through a tiny port before
sending it to the evaporator.
This type of expansion valve consists of a temperature
sensor, diaphragm, ball valve, ball seat, spring
adjustment screw, etc.
The temperature sensor contacts the evaporator outlet
pipe, and converts changes in temperature to pressure. It
then transmits these to the top chamber of the
diaphragm.
The refrigerant pressure is transmitted to the diaphragm’s
bottom chamber through the external equalizing pressure
tube.
The ball valve is connected to the diaphragm. The
opening angle of the expansion valve is determined by
the force acting on the diaphragm and the spring
pressure.