Part 2 of 2

General System Description
This carline uses the CCOT refrigerant system as described earlier in part 1 of General System Description. There are seven modes of operation available on the control. They are OFF, MAX, NORM, BI-LEVEL, VENT, HEAT and DEFROST. Blower speed is manually selected in all modes except off.

Air Conditioning Unit
This carline uses a modular type air conditioning unit. The module has the plenum chamber, blower assembly, evaporator core (plus accumulator/dehydrator) and the heater core in the engine compartment. The inlet and distributor case project into the passenger compartment. The unit is mounted in the dash using a single, double-lipped mounting gasket.

Plenum Chamber
The plenum chamber, located at the base of the windshield, is exposed to outside weather. Therefore, drainage has been provided to flush debris out of the bottom of the chamber through a drain hole. A flexible cover over the drain hole allows water to drain while preventing the entrance of under-car or engine compartment fumes.

Operating Assemblies and Control Valves
The operating assemblies and control valves of this carline air conditioning system are: Blower motor, evaporator core, heater core, temperature valve, air inlet valve, upper and lower mode valves, defroster valve, and the control assembly. Due to low available vacuum, the mode doors may be slow to respond with the blower motor speed switch set on high.

Control Assembly
The control assembly consists of a rotary select switch, blower switch, vacuum select valve, and a temperature lever vacuum valve. The hot water valve is open (no vacuum) with the temperature lever in the HOT position. Vacuum closes the hot water valve in the FULL COLD position.

Selector Positions
OFF
In the Off position the blower motor will not operate at any speed.
Max
In the MAX (air conditioning) position, the upper A/C mode valve opens, and the lower mode valve closes. Vacuum is applied to the heater water valve causing it to close. The recirculating/outside air valve closes allowing the air inside the car to be recirculated. The compressor clutch is engaged.
Norm
In the NORM (air conditioning) position, the upper A/C mode valve remains open, and the lower mode valve remains closed. No vacuum is applied to the heater water valve, this allows coolant to flow through the heater core. No vacuum is applied to the recirculating/outside air valve, this allows outside air to enter the car. The compressor clutch is engaged.
Bi-Level
In the BI-LEVEL (Air conditioning) position, the upper A/C mode valve remains open and the lower valve goes to a middle position between heat and A/C position. This allows air flow into the A/C and heater distribution area for bi-level cooling. The compressor clutch is engaged.
Vent
In the VENT (economy) position, the compressor is disengaged and the A/C mode doors are open. Outside air is drawn into the system through the evaporator core, past the heater core and out the A/C ducts, but is not cooled.
Heater
In the HEATER (economy) position, the A/C mode doors are closed and the air is directed through the heater outlets at a temperature determined by the position of the temperature valve. The compressor is OFF.
Def
In the DEF position, the defroster valve opens, blocking the heater outlet and directing most of the air out the defroster ducts. Also in the DEF position, the air conditioning system is operative (compressor is engaged) above 34°F - 39°F (l°C - 4°C) to help dehumidify the air.

Control Assembly Temperature Lever
The temperature of the air flow in all modes (exc. MAX.) is also controlled by the temperature lever of the control assembly. The temperature lever controls both the temperature door (through a cable) and a vacuum valve. The vacuum valve directs vacuum to the heater water valve with the temperature lever in the COLD position. This closes the hot water valve and prevents coolant flow through the heater core.