Control Assembly: Description and Operation

1. The heater box contains the fresh air blower, the heater core, and the evaporator for the A/C system.
2. The control flaps for air distribution are operated by vacuum servos, which are controlled by the vacuum distributor attached to the top lever in the control head.
3. The top lever also actuates the A/C thermostat switch to turn the air conditioning on and off.
4. The bottom lever of the control head is attached to the heater control valve by a cable. When the valve is open, engine coolant flows through the heater core to warm the incoming air.