System Operation

MAX A/C
When MAX A/C is selected:
- The air inlet duct door is at full vacuum, closing off outside air and admitting only recirculated air.
- The windshield defroster door is at full vacuum and the panel door is in the full vacuum position, directing airflow to the instrument panel A/C registers.
- The temperature is usually set for maximum cold (60°F) but may be heated if desired.
- Air will be picked up at the recirc opening by the blower motor. With the A/C control set for maximum cold, airflow across the evaporator core will be diverted past the heater core and then directed into the passenger compartment through the instrument panel A/C registers.
- The A/C compressor will be enabled when MAX A/C is selected.
- The blower motor is on.







NORM A/C
When NORM A/C is selected:
- The air inlet duct door is at no vacuum, admitting only outside air.
- The windshield defroster door is at full vacuum and the panel door is in the full vacuum position, directing airflow to the instrument panel A/C registers.
- The temperature is usually set for maximum cold (60°F) but may be heated if desired.
- Air will be picked up at the recirc opening by the blower motor. With the A/C control set for maximum cold, airflow across the evaporator core will be diverted past the beater core and then directed into the passenger compartment through the instrument panel A/C registers.
- The A/C compressor will be enabled when NORM A/C is selected.
- The blower motor is on.







VENT
When VENT is selected:
- The air inlet duct door is at the no vacuum position admitting outside air. From there, air flows through the system to the instrument panel A/C registers.
- The windshield defroster door is in the no vacuum position to block airflow to the heater outlet floor ducts.
- The heater air damper door is at full vacuum, directing airflow to the instrument panel registers. There is also some airflow to the A/C side window demisters.
- The temperature can be adjusted to heat the air but air cannot be cooled below outside temperature.
- The A/C compressor will be disabled when VENT is selected.
- The blower motor is on.







OFF
When OFF is selected:
- The air inlet duct door is at full vacuum closing off outside air and admitting only recirculated air.
- The heater air damper door is in the no vacuum position, closing off the passages to the instrument panel A/C registers.
- The blower motor and A/C compressor are off.







FLOOR
When FLOOR is selected:
- The air inlet duct door is in the no vacuum position blocking recirculated air and admitting outside air.
- The heater air damper door is in the no vacuum position, closing off airflow to the instrument panel registers.
- The windshield defroster door is in the full vacuum position blocking air to the defroster ducts and directing all airflow to the floor.
- The temperature can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature.
- - The A/C compressor will be disabled when FLOOR is selected.
- The blower motor is on.







FLOOR/DEFROST (EATC), MIX (MANUAL A/C)
When FLOOR/DEFROST (EATC) or MIX (Manual A/C) is selected:
- The air inlet duct door is in the no vacuum position blocking recirculated air and admitting outside air.
- The heater air damper door is in no vacuum position, blocking airflow to the instrument panel registers.
- The windshield defroster door is in the partial vacuum position directing airflow to both the windshield defroster hose nozzle and the floor duct.
- The A/C compressor will be enabled when FLOOR/DEFROST (EATC) or MIX (Manual A/C) is selected to dehumidify the air and reduce windshield fogging.
- The blower motor is on.







DEFROST
When DEFROST is selected:
- The air inlet duct door is in the no vacuum position admitting outside air.
- Both the heater air damper door and the windshield defrost door are in the no vacuum position directing air to the windshield defroster hose nozzle.
- The temperature setting will determine the amount of air that is directed through the heater core and the amount that bypasses the heater core.
- The A/C compressor will be enabled when DEFROST is selected to dehumidify the air and reduce windshield fogging.
- The blower motor is on.

Manual A/C Electrical Components:

With Manual A/C

EATC System Electrical Components, Part 1:

EATC System Electrical Components, Part 2:

With Electronic Automatic Temperature Control