FRONT BLOWER
With ignition on, battery voltage is applied to ignition load relay. Relay is energized, applying battery voltage to front blower motor relay. When front fan speed switch is turned to low position, ground is applied to front blower motor relay terminal No. 85 (Brown wire). Relay is energized, applying battery voltage to front blower motor terminal No. 2 (White/Red wire). Ground is applied to front blower motor through all 3 front blower resistor unit resistors. Front blower motor operates at low speed.
When front fan speed switch is turned to medium-low position, front blower motor relay remains energized. Battery voltage is still applied to front blower motor terminal No. 2 (White/Red wire). Ground is now applied to front blower motor through 2 resistors of front blower resistor unit and front fan speed switch. Motor operates at medium-low speed.
When front fan speed switch is turned to medium-high speed, front blower motor relay remains energized. Ground is now applied to front blower resistor unit and front fan speed switch. Motor then operates at medium-high speed. When front fan speed switch is turned to high speed, front blower motor relay remains energized. Ground is now applied directly to front blower motor through front fan speed switch. Motor operates at high speed.
TROUBLE SHOOTING
COLD AIR FROM HEATER (HEATER ON)
Start engine. Ensure coolant valve opens as temperature control is moved from COLD position. Check for mechanical fault in cooling system. Check heater lines, hoses, and heater core for blockage or restriction. Repair as necessary.
Oct 31, 2009 at 3:38 AM
