Isuzu Trooper 1999 Workshop Manual page 31

The air selector knob, with its different modes, also allows
you to select and maintain the most comfortable
passenger compartment temperature.
The air source select lever is used to select either
"FRESH" for the introduction of the outside air, or
"RECIRC" for the circulation of the inside air. When the
lever is set to "FRESH", the outside air is always taken
Legend
(1) Side Defroster Hose
(2) Vent Box
(3) Upper Center Vent Box
(4) Lower Center Vent Box
(5) Blower Assembly
(6) Control Lever Assembly
(7) Evaporator Assembly
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
into the passenger compartment. When setting the lever
to "RECIRC" position, the circulation of air is restricted
only to the inside air with no introduction of the outside air
and the air in the passenger compartment gets warm
quickly. However, the lever is normally set to "FRESH" to
prevent the windshield from clouding.
(8) Duct
(9) Heater Unit
(10) Rear Heater Duct
(11) Lap Vent Nozzle
(12) Vent Box
(13) Side Defroster Hose
(14) Defroster Nozzle
1A–3
840RS004