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Home >> Oldsmobile >> 1999 >> LSS V6-3.8L SC VIN 1 >> Repair and Diagnosis >> Heating and Air Conditioning >> Control Assembly >> Description and Operation >> HVAC System - Automatic >> Control Assembly Description (CJ2) >> Defog or Floor/Windshield
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Defog or Floor/Windshield

When the driver selects the DEFOG mode, the blower motor turns ON. The driver may manually adjust the blower speed by turning the fan speed knob. If the outside temperature is above 8°C (48°F), the following actions occur:
^ The A/C LED illuminates.
^ The compressor activates.

The compressor runs in order to maintain the evaporator core at about 1°C (33°F).

The heater and A/C programmer allows all of the vacuum actuators to vent the same as in the OFF mode:
^ The air inlet valve is in the outside air position.
^ The heater-A/C-bi-level valve is in the bi-level position.
^ The defrost-A/C valve is in the defrost position.

The blower pulls outside air into the system. The air is heated or cooled. The air is then forced through the windshield defroster and the floor outlets.

The heater and A/C programmer energizes the air mix actuator in order to perform the following functions:
1. Determine the proper air discharge temperatures
2. Position the air mix valves accordingly