All models use a blend-air system. Outside air enters heater through cowl opening and passes through a plenum chamber to heater core. A temperature control door in heater housing either directs incoming air through or around heater core.
Once past heater core, heated air and unheated air are mixed, producing air at desired temperature. Heater discharge is then directed through dash panel to air distribution duct in passenger compartment.
HEATER OUTPUT
Start engine. Allow engine to reach normal operating temperature. With engine at idle, set controls to maximum heat, floor and high blower positions. Using a thermometer, check air temperature coming from floor vents. See HEATER OUTPUT TEMPERATURE table.
If floor outlet air temperature is lower than specified, check cooling system and electric cooling fan. See ENGINE COOLING FAN article.
Check that both return and supply heater hoses are hot. If coolant return hose is much cooler than supply hose, repair coolant obstruction in heater system. Check for air flow obstruction in heater system. Check blend air door for proper operation.
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Monday, January 19th, 2009 AT 5:49 PM