First, feel the heater hoses going into the firewall under the hood. If they are hot, then you have hot engine coolant going into the heater core. If they are not hot, then you either have a bad thermostat or you are very low on engine coolant.
Next you need air flowing through the heater core so it can come out heated through your vents. If the iar is flowing somewhere else, your temp blend door is not moving because the bend door motor is bad or your temp knob on your heater controls is bad. The blend door motor is an electric motor.
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Air Flow Control
Air flow control is accomplished in the following manner:
- Primary control is through the function selector knob , mounted on the heater function selector switch, which is part of the heater control .
- The function selector knob has the following positions: OFF, PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST and DEFROST.
- The heater function selector switch combines a vacuum selector valve with an internal electrical switch.
- The vacuum selector valve directs source vacuum to various vacuum control motors (18A318) . Refer to the System Airflow Schematic and Vacuum Control Charts.
- An internal single-pole electrical switch is also controlled by the selector. The switch controls the electrical supply to the heater blower motor switch (18578) .
- The position of the function selector knob determines the manner in which the system will operate.
- Each position of the function selector knob is detented for positive engagement.
Temperature Control
The temperature control operates in the following manner:
- Temperature control of the heater system is determined by the position of the temperature control knob (between COOL-BLUE and WARM-RED) of the heater control .
- This control knob is connected to a potentiometer mounted in the heater control . This potentiometer is electrically connected to the electric blend door actuator that operates the A/C air temperature control door.
- Movement of the control knob from COOL (Blue) to WARM (Red) causes a corresponding movement on the air temperature control door and determines the temperature that the system will maintain.
System uses a reheat method to provide conditioned air to the passenger compartment.
- All airflow from the blower motor (18527) passes through the A/C evaporator housing .
- Temperature is then regulated by reheating a portion of the air and blending it with the remaining cool air to the desired temperature.
- Temperature blending is varied by the air temperature control door, which regulates the amount of air that flows through and/or around the heater core (18476) , where it is then mixed and distributed.
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inside you plenum box:
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