Savana 1/2 Ton Van V8-305 5.0L VIN M SFI (1998)
Heater Core: Description and Operation
Temperature Valve and Heater Core
The temperature of the air coming from the heater duct and defroster nozzle is regulated by controlling the relative amounts of warm and cool air coming
from the heater module. The amount of the total airflow that is allowed to pass through the heater core is governed by the temperature valve.
When the temperature knob in the control assembly is in the extreme left side of its travel, in the full "BLUE" (Cold) position, the temperature valve is
positioned to stop all of the airflow through the heater core so only unheated air is sent to the heater duct and defroster nozzle.
As the temperature knob is moved away from the full "BLUE" (Cold) position, the temperature valve opens to allow an increasing amount of air to pass
through the heater core. At the same time, the temperature valve reduces the amount of unheated air that is allowed to enter the mixture. This results in a
very responsive control of the temperature of the air discharged through the heater ducts and defroster nozzle.
When the temperature knob reaches the full "RED" (Hot) position to the extreme right end of its travel, the temperature valve in a position that diverts all
of the airflow through the heater core for maximum heating.
Hot coolant from the engine is directed through the heater core and returned to the cooling system when the engine is running.
