Without Air Conditioning

Flow Through Ventilation System (typical):

Heater System Air Flow (typical):

GENERAL DESCRIPTION
The base heater system is designed to provide heating, ventilation, windshield defrosting, and side window defogging.

The operation of the heater and vent system is controlled by the switches on the heater control assembly. The temperature valve motor and blower are connected electrically to the heater control assembly by a wiring harness. The blower circuit is non-functional in tile off mode and air flow is provided by the four blower speeds available in the remaining modes.

Temperature is controlled by the position of the temperature knob on the heater control assembly. This is electrically connected to the temperature valve motor which controls air flow through the heater core. Temperature valve position is independent of mode selection.

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

In the heat and defrost mode, outside air is driven by the blower to the temperature valve which, depending upon its position as controlled by tile 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 by the position of tile mode valve and control switch. A small amount of air is bled to the side window defogger system.