Isuzu Trooper (2000 year). Manual - part 16

 

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Isuzu Trooper (2000 year). Manual - part 16

 

 

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–33

Expansion Valve

This expansion valve (1) 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 (2).
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.
The expansion valve regulates the flow rate of the
refrigerant. Accordingly, when a malfunction occurs to
this expansion valve, both discharge and suction
pressure get low, resulting in insufficient cooling capacity
of the evaporator.
The calibration has been changed to match the
characteristics of HFC-134a.

874RY00003

Evaporator

The evaporator cools and dehumidifies the air before the
air enters the passenger compartment. High-pressure
liquid refrigerant flows through the expansion valve (2)
into the low-pressure area of the evaporator. The heat in
the air passing through the evaporator core (1) is lost to
the cooler surface of the core, thereby cooling the air.
As heat is lost between the air and the evaporator core
surface, moisture in the vehicle condenses on the outside
surface of the evaporator core and is drained off as water.
When the evaporator malfunctions, the trouble will show
up as an inadequate supply of cool air. The cause is
typically a partially plugged core due to dirt, or a
malfunctioning blower motor.
The evaporator core with a laminate louver fin is a
single-sided tank type where only one tank is provided
under the core.

874RY00007

Electronic Thermostat

The thermostat consists of the thermo sensor (1) and
thermostat unit (4) which functions electrically to reduce
the noises being generated while the system is in
operation.
The electronic thermo sensor (1) is mounted at the
evaporator core (2) outlet and senses the temperature of
the cool air from the evaporator (3). Temperature signals
are input to the thermostat unit. This information is
compared by the thermo unit and results in the output to
operate the A/C thermostat relay and turn the magnetic
clutch ON or OFF to prevent evaporator freeze-up.

1A–34 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

A characteristic of the sensor is that the resistance
decreases as the temperature increases and the
resistance increases as the temperature decreases.

874RX022

Refrigerant Line

Restriction in the refrigerant line will be indicated by:

1. Suction line — A restricted suction line will cause low

suction pressure at the compressor, low discharge
pressure and little or no cooling.

2. Discharge line — A restriction in the discharge line

generally will cause the discharge line to leak.

3. Liquid line — A liquid line restriction will be evidenced

by low discharge and suction pressure and
insufficient cooling.

Refrigerant flexible hoses that have a low permeability to
refrigerant and moisture are used. These low
permeability hoses have a special nylon layer on the
inside.

852RW011

Legend

(1) Pressure Resistance Layer (Polyester Braid)
(2) Moisture Resistance AND Outer Protector

Layer

(3) Heat Resistance Layer
(4) Heat Resistance Core Layer (Neoprene)
(5) Low Permeation Layer (Nylon Barner)

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–35

Air Conditioning Parts

852RW009

Legend

(1) Liquid Line (High-Pressure Pipe)
(2) O-ring
(3) Compressor
(4) Discharge Line (High-Pressure Hose)
(5) Pressure Switch
(6) Receiver Drier

(7) Condenser Assembly
(8) Drive Belt
(9) Relay

(10) Drain Hose

(11) Suction Line (Low-Pressure Hose)

(12) Evaporator Assembly
(13) A/C Switch

1A–36 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Wiring Diagram

D08RW254

 

 

 

 

 

 

 

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