Heater

MODES
The four modes of the base heater system (Vent, Heat, Defrost and Bi-Level) are controlled by the functional assemblies within the heater module. These assemblies are defined below:
1. Motor and Fan Assembly (Blower)
^ Provides and regulates air flow from the air inlet for further processing and/or distribution.
2. Heater Core
^ Transfers heat from engine coolant to inlet air, thus heating the inlet air.
3. Temperature Valve
^ Regulates the amount of air passing through the heater core, thus controlling the temperature and mix of heated and ambient air.
4. Mode (Defroster) Valve
^ Regulates the flow and distribution of processed air to the distribution (heater or defroster) ducts.

OPERATION
The operation of these assemblies is controlled by the levers and switch on the control assembly. The temperature lever operates a cable and the mode lever operates a vacuum control to select the appropriate mode.

The temperature cable has the slider-type, self- adjust feature. As the temperature lever of the control assembly is cycled through its full range of travel, the cable clip will assume a position assuring that the temperature valve will seat in both extreme positions. Blower speeds (OFF - LO - MED. 1 - MED. 2- HI) are controllable in all modes (VENT, HEAT, BI-LEVEL and DEFROST) by the switch on the control assembly.

Side window defogging is provided via ducts in the outboard corners of the instrument panel. Maximum air flow from these vents will be in the "Heater" mode with reduced air flow in the "Defrost" mode.

In the Heat, Bi-Level, Vent and Defrost mode, outside air is driven by the blower to the temperature valve which, dependent upon its position as controlled by the operator, distributes all or some portion of the inlet air through the heater core. The air is heated, mixed and then directed into either the defroster duct or the heater outlet depending on the position of the mode valve and control lever. A small amount of air is bled to the side window defogger system.