Heater Control Assembly

The five modes of the base heater system (Vent, Heat, Defrost, Bi-Level and Blend) 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 and Defrost and Heat Valves.

^ Regulate the flow and distribution of processed air to the distribution ducts.

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.

Four blower speeds are controllable in all functional modes by the switch on the control assembly.

Side window defogging is provided by 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, Blend 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, vent or the heater outlet depending on the position of the mode defrost and heat valves. A small amount of air is bled to the side window defogger system.

OPERATING TIPS

^ Clear snow and ice from the hood and air inlet in front of the windshield. This helps the heater and defroster work better and reduces the chance of fogging the inside of the windshield.
^ Run the fan on "HI" for a few moments before driving off. This helps clear the intake ducts of snow and moisture and reduces the chance of fogging the inside of the windows.
^ Always keep the front inlet grilles clear of obstructions (leaves, ice, snow, etc).
^ Always keep the underseat air path clear of objects.