Receiver / Drier; Pressure Switch - Isuzu Trooper 1999 Workshop Manual

1A–32 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
The refrigerant line connection has a bolt at the block
joint, for easy servicing.
The condenser assembly (6) is located in front of the
radiator. It provides rapid heat transfer from the
refrigerant to the cooling fins.

Receiver / Drier

The receiver/drier (5) performs four functions:
f 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.
f The liquefied refrigerant from the condenser is mixed
with refrigerant gas 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.
f The receiver/drier utilizes a filter and drier to remove
the dirt and water mixed in the cycling refrigerant.
f The sight glass, installed on top of the receiver/drier,
shows the state of the 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.

Pressure Switch

The pressure switch (Dual pressure switch) (4) is
installed on the upper part of the receiver/drier, to detect
excessively high pressure (high pressure switch) and
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prevent compressor seizure due to the refrigerant leaking
(low pressure switch), so that the compressor is able to be
turned "ON" or "OFF".
The pressure characteristics of HFC-134a refrigerant
differ from those of R-12. Thus, the pressure switch
operation for HFC-134a systems has been changed from
R-12.
Compressor
Low-pressure
control
High-pressure
control
ON OFF
(kPa/psi) (kPa/psi)
186.3 29.4 176.5 19.6
(27.0 4.3) (25.6 2.8)
2353.6 196.1 2942.0 196.1
(341.3 28.4) (426.6 28.4)
875RW004
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