Heater

MODES
The three modes of the base heater system (Vent, Heat, Defrost) 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.
5. Vent Valve regulates the flow of non-processed (outside) air into the passenger compartment.

COMPONENTS DESCRIPTION
The operation of these assemblies is controlled by the levers and switch on the control assembly. Depending on model application, 2 or 3 indexed snap-in cables are attached to the module and control levers.

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. The vent and/or defrost cables also have the self-adjusting feature. Blower speeds (OFF - LO - MED - HI) are controllable in all modes (VENT, HEAT, and DEFROST) by the switch on the control assembly.

Blending air between modes can be done by varying the mode selector. Varying the selector tween "Heat" and "Defrost" will allow more air or less air to be directed out either the defroster outlet or e heater outlet. The closer the mode selector is sitioned to the "Heater" position, the larger the amount of air coming out the heater outlet. The closer the mode selector is positioned to "Defrost," the larger the amount of air going to the windshield. The temperature of this air is governed by the temperature lever position.

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.

Varying the mode selector between "Heater" and "Vent" positions likewise varies the proportion of air coming out the heater outlet and the center vent outlets. With the selector in some midway position, air coming out the center vent outlets will be ambient temperature, while air out the heater outlet will be mixed warm air, its temperature depending on temperature lever position.

In the Heat and Defrost mode, outside air is driven by the blower to the temperature valve which is dependent upon its position as controlled by the operator, distributes all or some portion of the inlet air through the heater core. The vent valve will prevent air entry into the vent duct and direct this ambient air to the mix portion of the heater module. The air is thus 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.