Auxiliary A/C System

AIR CONDITIONING AND HEATING SYSTEM
The auxiliary air conditioning and heating system is available as an option for this application. It uses a A/C evaporator expansion valve to meter refrigerant into the auxiliary system A/C evaporator core but relies on the primary air conditioning system to circulate and remove heat from the refrigerant.

The auxiliary air conditioning and heating system has the following features:
- split-case evaporator housing with integral heater core and blower motor.
- located along the left side of the vehicle behind the driver.
- recirculates inside vehicle air only; outside air is not available.
- independently adjustable blower motor speeds.

The system major components are:
- evaporator housing
- A/C evaporator core
- heater core
- blower motor
- heater air outlet door
- heater air outlet door vacuum control motor
- rear seat airflow duct
- pillar duct
- overhead duct integral to the headliner
- A/C registers
- in-line refrigerant filter assembly

SYSTEM OPERATION
System operation is as follows:
- Primary control is from the A/C control mounted in the instrument panel.
- When the function selector knob is in the OFF position, the A/C compressor does not run and both primary and auxiliary blower motors are OFF.
- When the function selector knob is in VENT or FLOOR position, the A/C compressor is off and power is available for operation of the auxiliary blower motor.
- When the function selector knob is in MAX A/C, A/C, PANEL/FLOOR, FLOOR/DEFROST or DEFROST position, the A/C compressor is on and power is available for operation of the auxiliary blower motor.
- When the front auxiliary blower motor switch knob is in the REAR CTRL position, control of the auxiliary blower motor is transferred to the rear heater blower motor switch.
- When the front auxiliary blower motor switch knob is in any position other than REAR CTRL, the rear heater blower motor switch is disabled.
- On late production vehicles, air discharge can be independently directed and auxiliary blower motor control transferred to the rear heater blower motor switch, by selecting REAR CTRL (blue or red) positions.
- The front auxiliary blower switch provides three speeds (MED-LO, MED-HI and HI) and the rear heater blower motor switch provides four speeds (LO, MED-LO, MED-HI and HI) in addition to OFF.
- The heater blower motor switch resistor is mounted in the auxiliary system evaporator housing in the airflow stream.

SYSTEM AIR FLOW
The auxiliary air conditioning and heating system has three modes of operation as determined by the function selector and auxiliary blower switch positions located on the A/C control in the instrument panel.







- Vacuum Control Diagram - Early Production







- Vacuum Control Chart - Early Production


On early production vehicles:
- Function selector in the OFF, FLOOR, FLOOR/DEFROST or DEFROST positions; the vacuum operated heater air outlet door is in the no-vacuum position, directing all airflow through the heater core and out the rear seat airflow duct.
- Function selector in the MAX A/C or A/C position; the vacuum operated heater air outlet door is in the vacuum position, directing all airflow through the A/C evaporator core and out the belt line and overhead A/C registers. The A/C compressor is on for cooling of the recirculated airflow.
- Function selector in the PANEL or PANEL/FLOOR position, airflow is the same as MAX A/C or A/C, but the A/C compressor is not operating to cool the airflow.







- Vacuum Control Diagram - Late Production







- Vacuum Control Chart - Late Production


On late production vehicles:
- When the front auxiliary blower motor switch knob is in the red dots, the vacuum operated heater air outlet door is in the no-vacuum position, directing all airflow through the heater core and out the rear seat airflow duct.
- When the front auxiliary blower motor switch knob is in the blue dots, the vacuum operated heater air outlet door is in the vacuum position, directing all airflow through the A/C evaporator core and out the belt line and overhead A/C register.
- Function selector in the OFF, PANEL or FLOOR position, the A/C compressor is not operating to cool the airflow.