Electronic Thermostat; Refrigerant Line - Isuzu Trooper 1999 Workshop Manual

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

Electronic Thermostat

The thermostat consists of the thermo sensor (2) and
thermostat unit (4) which functions electrically to reduce
the noises being generated while the system is in
operation.
The electronic thermo sensor (2) is mounted at the
evaporator core (1) 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.
A characteristic of the sensor is that the resistance
decreases as the temperature increases and the
resistance increases as the temperature decreases.

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
permeability hoses have a special nylon layer on the
inside.
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)
874RW016
moisture are used. These low
852RW011